Dtv transmitting system and receiving system and method of processing broadcast signal

ABSTRACT

A DTV transmitting system includes a pre-processor, a block processor, and a trellis encoder. The pre-processor pre-processes enhanced data by expanding the enhanced data at an expansion rate of 1/H. The block processor includes a first converter, a symbol encoder, a symbol interleaver, and a second converter. The first converter converts the expanded data into symbols. The symbol encoder encodes each valid enhanced data bit in the symbols at an effective coding rate of 1/H. The symbol interleaver interleaves the encoded symbols, and the second converter converts the interleaved symbols into enhanced data bytes. The trellis encoder trellis-encodes the enhanced data outputted from the block processor.

This application claims the benefit of the Korean Patent Application No.10-2006-0037181, filed on Apr. 25, 2006, which is hereby incorporated byreference as if fully set forth herein. Also, this application claimsthe benefit of the Korean Patent Application No. 10-2006-0089736, filedon Sep. 15, 2006, which is hereby incorporated by reference as if fullyset forth herein. This application also claims the benefit of U.S.Provisional Application No. 60/821,248, filed on Aug. 2, 2006, which ishereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital television (DTV) transmittingsystem and receiving system and a method of processing a broadcastsignal.

2. Discussion of the Related Art

Presently, the technology for processing digital signals is beingdeveloped at a vast rate, and, as a larger number of the population usesthe Internet, digital electric appliances, computers, and the Internetare being integrated. Therefore, in order to meet with the variousrequirements of the users, a system that can transmit diversesupplemental information in addition to video/audio data through adigital television channel needs to be developed.

Some users may assume that supplemental data broadcasting would beapplied by using a PC card or a portable device having a simple in-doorantenna attached thereto. However, when used indoors, the intensity ofthe signals may decrease due to a blockage caused by the walls ordisturbance caused by approaching or proximate mobile objects.Accordingly, the quality of the received digital signals may bedeteriorated due to a ghost effect and noise caused by reflected waves.However, unlike the general video/audio data, when transmitting thesupplemental data, the data that is to be transmitted should have a lowerror ratio. More specifically, in case of the video/audio data, errorsthat are not perceived or acknowledged through the eyes or ears of theuser can be ignored, since they do not cause any or much trouble.Conversely, in case of the supplemental data (e.g., program executionfile, stock information, etc.), an error even in a single bit may causea serious problem. Therefore, a system highly resistant to ghost effectsand noise is required to be developed.

The supplemental data are generally transmitted by a time-divisionmethod through the same channel as the video/audio data. However, withthe advent of digital broadcasting, digital television receiving systemsthat receive only video/audio data are already supplied to the market.Therefore, the supplemental data that are transmitted through the samechannel as the video/audio data should not influence the conventionalreceiving systems that are provided in the market. In other words, thismay be defined as the compatibility of broadcast system, and thesupplemental data broadcast system should be compatible with thebroadcast system. Herein, the supplemental data may also be referred toas enhanced data. Furthermore, in a poor channel environment, thereceiving performance of the conventional receiving system may bedeteriorated. More specifically, resistance to changes in channels andnoise is more highly required when using portable and/or mobilereceiving systems.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a DTV transmittingsystem and receiving system and a method of processing a broadcastsignal that substantially obviate one or more problems due tolimitations and disadvantages of the related art.

The present invention is to provide a DTV transmitting system andreceiving system and a method of processing a broadcast signal, whichare suitable for transmission of enhanced data and resistant againstnoise.

The present invention is to provide a DTV transmitting system andreceiving system and a method of processing a broadcast signal, whichare capable of performing additional encoding and stratifying forenhanced data, according to degree of importance of the enhanced data,and transmitting it, thereby enhancing receiving performance of areceiving system.

Yet another object of the present invention is to provide a DTVtransmitting system and receiving system and a method of processing abroadcast signal, which are capable of stratifying known data, which areidentified at transmitting/receiving ends, and enhanced data, andmultiplexing them with main data, thereby enhancing receivingperformance.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, adigital television (DTV) transmitting system includes a pre-processor, ablock processor, and a trellis encoder. The pre-processor pro-processesenhanced data by coding the enhanced data for forward error correction(FEC) and expanding the FEC-coded enhanced data at an expansion rate of1/H. The block processor codes a block of the pre-processed enhanceddata, and the trellis encoder trellis-encodes the coded block of thepre-processed enhanced data.

The block processor includes a first converter, a symbol encoder, asymbol interleaver, and a second converter. The first converts theexpanded enhanced data into corresponding symbols. The symbol encoderencodes the converted symbols. The symbol encoder encodes each validenhanced data bit in the converted symbols at an effective coding rateof 1/H. In a first example, the symbol encoder may encode each validenhanced data bit in the symbols at a coding rate of 1/2 twice in orderto result an effective coding rate of 1/4. In a second example, it mayencode each valid enhanced data bit at a coding rate of 1/2 and repeatthe encoded data bits once in order to result the same effective codingrate. Alternatively, it may simply encode each valid enhanced data bitat a coding rate of 1/4 to result the same effective coding rate.

In another aspect of the present invention, a DTV receiving systemincludes a tuner, a demodulator, a channel equalizer, and a blockdecoder. The tuner tunes to a channel to receive a digital broadcastsignal including enhanced data. The demodulator demodulates the receivedbroadcast signal, and the channel equalizer compensates channeldistortion of the demodulated signal. The block decoder decodes a blockof enhanced data symbols included in the channel-equalized signal. Itincludes a trellis decoder, a symbol deinterleaver, and a symboldecoder. The trellis decoder performs trellis-decoding on the block ofenhanced data symbols. The symbol deinterleaver deinterleaves thetrellis-decoded enhanced data symbols. The symbol decoder furtherdecodes the deinterleaved symbols.

In order to perform turbo decoding on the block of enhanced datasymbols, the block decoder may further include a symbol interleaverinterleaving the symbols decoded by the symbol decoder, and amultiplexer multiplexing the interleaved symbols with the block ofenhanced data symbols.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a schematic block diagram of a digital broadcasttransmitting system according to an embodiment of the present invention;

FIG. 2 illustrates a detailed diagram of a Trellis encoding unit of FIG.1 according to an embodiment of the present invention;

FIG. 3 illustrates a representation of data configuration at an inputend of a data interleaver in a digital broadcast transmitting systemaccording to the present invention;

FIG. 4 illustrates a representation of data configuration at an outputend of a data interleaver in a digital broadcast transmitting systemaccording to the present invention;

FIG. 5 illustrates a data group according to the present invention;

FIG. 6 and FIG. 7 illustrate schematic block diagrams of embodiments ofthe pre-processor of FIG. 1;

FIG. 8 and FIG. 9 illustrate schematic block diagrams of embodiments ofthe block processor according to the present invention;

FIG. 10 and FIG. 11 illustrate schematic block diagrams of a symbolencoder according to the present invention;

FIG. 12 illustrates diagram for describing symbol interleaving accordingto the present invention;

FIG. 13 illustrates a schematic block diagram of a demodulating unitincluded a digital broadcast receiving system according to an embodimentof the present invention;

FIG. 14 illustrates a schematic block diagram of the block decoder ofFIG. 13;

FIG. 15 illustrates a block diagram of a transmitting system accordingto another embodiment of the present invention;

FIG. 16A and FIG. 16B illustrate examples of data configuration atbefore and after ends of a data interleaver in a transmitting systemaccording to the present invention;

FIG. 17 illustrates a block diagram showing a general structure of ademodulating unit within a receiving system according to anotherembodiment of the present invention;

FIG. 18 illustrates a block diagram showing the structure of a receivingsystem according to an embodiment of the present invention; and

FIG. 19 illustrates a block diagram showing the structure of a receivingsystem according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

The terminologies disclosed the present application is widely used inthis field of the present invention. However, some of them are definedby the inventors. In this case, the newly defined terminologies aredescribed in detail in the following description. Therefore, theterminologies in the present invention will be understood on the basisof the disclosure of the present application.

Enhanced data in the present application may be any of applicationprogram execution files, data having information, such as stockinformation, etc., and video/audio data. Known data may be data which ispreviously known in transmitting/receiving ends, based on a protocol.Main data is indicative of data which can be received by theconventional receiving systems, including video/audio data.

The present invention serves to identify enhanced data havinginformation according to predetermined conditions, and to individuallyor integratedly perform additional encoding for the identified enhanceddata, respectively. Here, the conditions for identifying the types ofthe enhanced data may be determined by many factors. For example, theenhanced data may be identified by degree of importance thereof. Here,the enhanced data can be transmitted on the basis of a format ofenhanced data having information as well as a format of enhanced datahaving video/audio data.

In order to group a plurality of enhanced data packets, multiplex thegroup with main data, and transmit them, the present inventionstratifies the group to form a plurality of regions, and classifiestypes of inserted data, and processing methods, etc., according tocharacteristics of stratified regions.

In addition, the present invention can classify enhanced data into Ntypes of enhanced data, from high priority to low priority. On the otherhand, although the present invention will be described on the basis ofthe high priority enhanced data and the low priority enhanced data for aconvenient description, it will be easily appreciated that such animplementation is just an embodiment, and there may be many embodimentsmodified therefrom. Therefore, the present invention must not be limitedby such embodiments.

FIG. 1 illustrates a schematic block diagram of a digital broadcasttransmitting system according to an embodiment of the present invention.Namely, the digital broadcast transmitting system inputs the identifiedenhanced data, performs additional encoding for the inputted enhanceddata, individually or integratedly, and then multiplexes the encodedresult with main data to transmit it.

The digital broadcast transmitting system includes a pre-processor 101,a packet formatter 102, a packet multiplexer 103, a data randomizer 104,a scheduler 105, a post-processor 110, an RS encoder/non-systematic RSencoder 121, a data interleaver 122, a parity replacer 123, anon-systematic RS encoder 124, a Trellis encoding unit 125, a framemultiplexer 126, and a transmitting unit 130.

The pre-processor 101 inputs enhanced data and then performspre-processing, such as additional block encoding, block interleaving,byte expansion through insertion of null data, etc. Afterwards, thepre-processing result is outputted to the packet formatter 102.

Here, when the inputted enhanced data is the high priory enhanced dataand the low priority enhanced data, the pre-processor 101 performspre-processing, such as additional block encoding, block interleaving,byte expansion, etc., respectively. After that, the data, which isclassified by degree of importance, is outputted to the packet formatter102 while its classified state is kept. The operations of thepre-processor 101 will be described in detail later.

The packet formatter 102 collects the pre-processed enhanced data on thebasis of packet unit, to group them, according to control of thescheduler 105. Here, the packet is indicative of an enhanced data packetof 188 byte unit as MPEG header of 4 bytes is added thereto. Theenhanced data packet can be composed of only enhanced data or only knowndata (or known data places). Also, the enhanced data packet can becomposed of a result that the enhanced data and the known data aremultiplexed. Also, the enhanced data packet may include aninitialization data place holder for a Trellis memory, which will bedescribed later.

Later, there may be a detailed description for a rule related toformation of data groups in the packet formatter 102.

The packet formatter 102 outputs its output to the packet multiplexer103. The packet multiplexer 103 performs time divisional multiplexingfor the main data packet and the data group, on the basis of TransportStream (TS) packet unit, to output them to the data randomizer 104,according to control of the scheduler 105.

Here, the scheduler 105 generates and outputs a control signal such thatthe packet formatter 102 can multiplex the enhanced data, the known data(or known data place holder), and an initialization data place holder.Also, the scheduler 105 generates and outputs a control signal such thatthe packet multiplexer 103 can multiplex the main data packet and thedata group on the basis of packet unit.

The data randomizer 104 deletes MPEG synchronization bytes from the dataand randomizes the remaining 187 bytes using a pseudo random bytegenerated therein. After that, the randomization result is outputted tothe post-processor 110.

The post-processor 110 includes an RS encoder/non-systematic RS parityplace holder inserter 111, a data interleaver 112, a block processor113, a data deinterleaver 114, and an RS byte remover 115.

The RS encoder/non-systematic RS parity place holder inserter 111performs systematic RS encoding when the randomized data is a main datapacket, and non-systematic RS parity holder insertion when therandomized data is an enhanced data packet. Namely, like theconventional broadcast system, the RS encoder/non-systematic RS parityplace holder inserter 111 performs systematic RS encoding when thepacket of 187 bytes, which is outputted from the data randomizer 104, isa main data packet, and then adds a parity of 20 bytes to the end of the187 byte data, to output it to the data interleaver 112.

On the other hand, the RS encoder/non-systematic RS parity place holderinserter 111 inserts an RS parity place holder, which is composed ofnull data of 20 bytes, into a packet to perform non-systematic RSencoding, when the packet of 187 bytes, which is outputted from the datarandomizer 104, is an enhanced data packet. Also, the RSencoder/non-systematic RS parity place holder inserter 111 inserts thebytes of the enhanced data packet in the places of the remaining 187bytes to output them to the data interleaver 112.

The data interleaver 112 performs data interleaving for the output ofthe RS encoder/non-systematic RS parity place holder inserter 111 andthen outputs the data interleaving result to the block processor 113.

The block processor 113 performs additional encoding for only theenhanced data, which is outputted from the data interleaver 112, andthen outputs it to the data interleaver 114. The data deinterleaver 114performs data deinterleaving for the inputted data and then outputs itto the RS byte remover 115. Here, the data deinterleaver 114 performs areverse operation of the data interleaver 112. The additional encodingprocess of the block processor 113 will be described in detail later.

The RS byte remover 115 deletes the parity of 20 bytes, which is addedin the RS encoder/non-systematic RS parity place holder inserter 111.Here, when the inputted data is a main data packet, last 20 bytes of the207 bytes are deleted, and when the inputted data is an enhanced datapacket, the parity place holders of 20 bytes of 207 bytes are deleted,in which the parity place holders of 20 bytes are inputted to performnon-systematic RS encoding. Such processes are performed to re-calculatea parity since the original data is changed by the block processor 113in the case that the inputted data is enhanced data.

The RS byte remover 115 outputs its output to the RSencoder/non-systematic RS encoder 121.

The RS encoder/non-systematic RS encoder 121 adds a parity of 20 bytesin the packet of 187 bytes, which is outputted from the RS byte remover115, and then outputs it to the data interleaver 122. Here, like theconventional broadcast system, the RS encoder/non-systematic RS encoder121 performs systematic RS encoding to add a parity of 20 bytes to theend of the data of 187 bytes, when the inputted data is a main datapacket. When the inputted data is an enhanced data packet, the RSencoder/non-systematic RS encoder 121 determines 20 places for paritybyte in the packet and then inserts the RS parity of 20 bytes in thedetermined parity byte place, in which the RS parity of 20 bytes areobtained through non-systematic RS encoding.

The data interleaver 122 is implemented with a convolution interleaverof byte unit, and is operated by the interleaving rule like the datainterleaver 112.

The data interleaver 122 outputs its output to the parity replacer 123and the non-systematic RS encoder 124.

It is necessary to initialize a memory of a Trellis encoding unit 125such that the output data of the Trellis encoding unit 125, which islocated the rear end of the parity replacer 123, is used as known datadefined in transmitting/receiving ends. Namely, the memory of theTrellis encoding unit 125 must be initialized before the inputted knowndata sequence is processed by Trellis encoding.

Here, the beginning portion of the inputted known data sequence is notactual known data but the initialization data place holder which isinserted thereto in the packet formatter 102. Namely, one known datasequence is composed of initialization data place holders and actualknown data. Therefore, it is necessary to generate initialization dataimmediately before the inputted known data sequence is processed byTrellis encoding and then to replace the initialization data placeholder of a corresponding Trellis memory with the generatedinitialization data. Such processes are performed to maintaincompatibility with the reverse direction of the conventional receivingsystem.

After that, the initialization data of the Trellis memory is generatedsuch that the memory of the Trellis encoding unit 125 is initializedbased on the past state of the memory. Also, the RS parity affected bythe replaced initialization data is re-calculated and then there-calculated RS parity is replaced with the RS parity outputted fromthe data interleaver 122.

Therefore, the non-systematic RS encoder 124 inputs a non-systematic RSparity from the data interleaver 122 and initialization data from theTrellis encoding unit 125, and calculates a new non-systematic RS parityto output it to the parity replacer 123. Here, the non-systematic RSparity is previously calculated for an enhanced packet in whichinitialization data place holder to be replaced with the initializationdata is included. Then, the parity replacer 123 is operated such thatdata in the enhanced data packet selects the output of the datainterleaver 122 and the RS parity selects the output of thenon-systematic RS encoder 124, thereby outputting the selected outputsto the Trellis encoding unit 125.

On the other hand, when the parity replacer 123 inputs main data packetor an enhanced data packet in which an initialization data place holderto be replaced is not included, it selects the data outputted from thedata interleaver 122 and the RS parity and then outputs them to theTrellis encoding unit 125 without change.

The Trellis encoding unit 125 converts data of byte unit to data ofsymbol unit and performs 12-way interleaving therefor. Afterwards, theinterleaving result is processed by Trellis encoding and then outputtedto the frame multiplexer 126. The detailed configuration of the Trellisencoding unit 125 will be described later.

The frame multiplexer 126 inserts a field synchronization and a segmentsynchronization in the output of the Trellis encoding unit 125 and thenoutputs it to the transmitting unit 130. The transmitting unit 130includes a pilot inserter 131, a modulator 132, and an RF converter 133.Since the operations of the transmitting unit 130 are the same that asthe conventional ones, a description therefor will be omitted in thisdisclosure.

Trellis Initialization

FIG. 2 illustrates a detailed diagram of a Trellis encoding unit 125 ofFIG. 1 according to an embodiment of the present invention.

The Trellis encoding unit 125, which can be initialized, includes abyte-symbol converter 201, a multiplexer 202, a Trellis encoder 203 forinputting inputs which are selected as the Trellis encoder 203 operates,and a symbol-byte converter 204 for converting symbol data to data ofbyte unit and outputting it to the non-systematic RS encoder 124, inwhich the symbol data is used to initialize the Trellis encoder 203.

The byte-symbol converter 201 inputs the output data of the parityreplacer 123, on the basis of byte unit, and converts it to symbol unit.After that, the converting result is interleaved and then outputted tothe multiplexer 202.

Generally, the output of the byte-symbol converter 201 is selected bythe multiplexer 202 and then outputted to the Trellis encoder 203.However, when the interleaved data is known data, and the known data isan initialization data place holder which is included in the beginningof the successively inputted known data sequence, the Trellis encoder203 must be initialized.

Such processes are needed because the Trellis encoder 203 has a memoryand thus its next output is dependent on the present input as well asthe present state of the memory. Therefore, in order to outputpredetermined data (i.e., known data) at a certain time, the memory ofthe Trellis encoder 203 must be initialized.

Namely, so that the memory of the Trellis encoder 203 can beinitialized, the packet formatter 103 inserts an initialization dataplace holder in the beginning portion of the known data sequence,according to a data group rule. Then, the initialization data placeholder is replaced with an initialization symbol in the Trellis encoder203. Afterwards, the memory of the Trellis encoder 203 is initialized onthe basis of the initialization data. Therefore, from the time point ofthe initialization, the output of the Trellis encoder 203 can be theknown data which is encoded to comply with the transmitting/receivingends.

The Trellis encoder 203 can generate an input symbol value forinitialization according to its own memory value. Afterwards, thegenerated symbol value is outputted to the multiplexer 202 and thesymbol-byte converter 204.

The multiplexer 202 selects an initialization symbol instead of theinputted symbol to output them to the Trellis encoder 203, when theinputted data, which is interleaved and converted to a symbol, is aninitialization data place holder. Here, the initialization symbol isoutputted from the Trellis encoder 203. For the other cases, themultiplexer 202 selects the symbols outputted from the byte-symbolconverter 201 and then outputs them to the Trellis encoder 203.

The symbol-byte converter 204 inputs initialization symbols outputtedfrom the Trellis encoder 203 and then performs 12-way deinterleavingtherefor to convert them to symbol byte unit. After that, the convertingresult is outputted to the non-systematic RS 124 to re-calculate an RSparity.

Pre-Process

FIG. 3 and FIG. 4 illustrate representations of data configuration atinput and output ends of data interleavers 112 and 122, respectively, ina digital broadcast transmitting system according to the presentinvention. More specifically, as shown in FIG. 3, the data interleaverinputs data, based on packet sequence, from top to bottom and from leftto right. Also, as shown in FIG. 4, the data interleaver outputs datafrom top to bottom and from left to right. Namely, as shown in FIG. 3,the data interleaver outputs A first, and then combination of B and C,combination of D and E, and F last, thereby outputting data as shown inFIG. 4.

Afterward, when main data and enhanced data are multiplexed on the basisof packet unit, and then a plurality of enhanced data packets aregrouped to be transmitted, 104 packets of A, B, C, and D are formed as asingle data group and then transmitted, as shown in FIG. 3. In thiscase, when analyzing configuration of the output data of the datainterleaver of FIG. 4, the enhanced data in the regions B and C can becontinuously and successively outputted, but the enhanced data in theregion A or D can be outputted thereto, in a state in which the enhanceddata is combined with main data.

In the present invention, the data group is stratified into three parts,Head, Body and Tail. Namely, on the basis of output of the datainterleaver, the Head is firstly outputted from the data group, the Bodyis outputted after the Head, and the Tail is outputted last. Here, onthe basis of the time after performing data interleaving, the Body isallocated to include a part of or all of the regions where the enhanceddata in the data group are continuously and successively outputted.Here, the Body may include a region where enhanced data isnon-continuously outputted.

FIG. 5 illustrates a data group according to the present invention, inwhich a predetermined number of enhanced data packets form a group, suchthat the group can be divided into Head, Body, and Tail regions.

Left figure of FIG. 5 shows data configuration before performing datainterleaving, and right figure of FIG. 5 shows data configuration afterperforming data interleaving.

FIG. 5 illustrates a diagram for describing a case where 104 packetsform a data group. Since the data interleaver is periodically operatedon the basis of 52 packet units, the data group can be formed on thebasis of 52 packet times.

Also, as shown in FIG. FIG. 5, the Body region for configuration ofdata, which is outputted from the output end of the data interleaver,forms a rectangular shape. Namely, the Body region is set in the datagroup, such that it cannot be mixed in the main data region while it isprocessed, but it can be formed by only enhanced data.

The data group is divided into three regions to be used for differentpurposes. Namely, since the regions corresponding to the Bodies of FIG.5 are configured by only enhanced data without interference of main datawhile they are processed, they have relatively high receivingperformance. On the other hand, since the enhanced data in the Head andTail regions may be mixed with main data while the outputs are outputtedfrom the data interleaver, the receiving performance of the Head andTail regions is relatively lower than that of the Body region.

In addition, in a system in which known data is inserted in the enhanceddata and then transmitted, when successive long segments of known dataare periodically inserted to the enhanced data, the enhanced data can beinserted to a region in which main data is not mixed therewith, on thebasis of the output sequence of the data interleaver. Namely, as shownin FIG. 5, known data with a predetermined length can be periodicallyinserted to the Body regions. However, it is difficult to periodicallyinsert the known data to the Head and Tail regions, and also, it isimpossible to continuously insert a relatively long segment of knowndata thereto. Here, the initialization data place holder forinitializing the memory of the Trellis encoder 203 is allocated to thebeginning portion of the known data sequence.

Also, when an enhance data group is divided into Head, Body and Tailregions, the respective regions can take charge of different services.For example, when enhanced data is divided into high priority enhanceddata and low priority enhanced data, the high and low priority enhanceddata can be allocated to proper regions of the Head, Body and Tailregions in the data group, respectively. Namely, the high priorityenhanced data is allocated to the Body region and the low priorityenhanced data is allocated to the Head and Tail regions.

Therefore, when the enhanced data is inputted, the pre-processor 101 canperform pre-processes for the inputted enhanced data, such as blockencoding, block interleaving, byte expansion, etc., considering types ofinputted enhanced data and types of data allocated to the respectiveregions in the data group. Also, the pre-processor 101 can performpre-processes for the inputted enhanced data, considering one of typesof inputted enhanced data and types of data allocated to the respectiveregions in the data group.

FIG. 6 and FIG. 7 illustrate schematic block diagrams of embodiments ofthe pre-processor 101 of FIG. 1. More specifically, FIG. 6 shows apre-processor for integratedly performing pre-process regardless oftypes of inputted enhanced data, and FIG. 7 shows an pre-processor forindividually performing pre-processes according to types of inputtedenhanced data.

As shown in FIG. 6, the pre-processor 101 includes a block encoder 501,a block interleaver 502, and a byte expansion unit 503.

The block encoder 501 serves to encode inputted enhanced data on thebasis of block encoding. For example, the block encoder 501 isimplemented with an RS encoder, a convolution encoder, a low densityparity check (LDPC) encoder, etc., which can use block codes. Also, theblock encoder may selectively adopt a block interleaver 502 according toimplementation objectives.

Application of the block interleaving is related to entire systemperformance. For example, random interleaving, etc., can be usedtherefor.

Here, so that the block encoder 501 performs encoding on the basis ofblock unit and the block interleaver 502 performs block interleaving,block size must be determined.

For example, the block size may be set to bit number of enhanced dataincluded in the Body region in the data group, and also the block sizemay be set to bit number of enhanced data included in the Head and Tailregions. Here, the block size for enhanced data in the Body region isapproximately similar to that in the Head and Tail regions. Suchrelation can be shown in FIG. 5. On the other hand, the block sizes arejust an embodiment of the present invention. For example, when thebeginning and end of a block are determined such that the enhanced datacan have limited lengths, any size of blocks can be chosen. Therefore,the present invention will not be limited by such embodiments.

After encoding on the basis of a block coding fashion, the blockinterleaved data undergoes byte expansion through insertion of null bitsin the byte expansion unit 503. Here, the byte expansion unit 503, whichis implemented as an embodiment of the present invention, can extend onebyte to two bytes, four bytes, or any bytes, as at least one ofinsertion of null bits and a repetition operation is performed.

As shown in FIG. 7, the pre-processor 101 includes a certain number ofblock encoders, a certain number of block interleavers and a certainnumber of a byte expansion unit, based on the number N of types ofenhanced data, such that the respective elements can performpre-processes. Here, according to types of enhanced data, the blockencoders, block interleavers and byte expansion units perform differentblock encodings, block interleavings, and byte expansions.

When the enhanced data is classified into high priority enhanced dataand low priority enhanced data, the pre-processor 101 includes at leasttwo encoders each of which is formed by a block encoder, a blockinterleaver and a byte expansion unit.

As shown in FIG. 7, a first encoder denoted by reference numeral 510encodes high priority enhanced data to perform byte expansion therefor,and a second encoder denoted by reference numeral 5N0 encodes lowpriority enhanced data to perform byte expansion therefor. Also, thehigh priority enhanced data is allocated to the Body region in the datagroup in the packet formatter 102 and the low priority enhanced data isallocated to the Head and Tail regions.

In this case, the encoding rate of the block encoder 511 in the firstencoder 510 is set higher than that of the block encoder 5N1 in thesecond encoder 5N0, such that the data transmission rate can beincreased. Because relatively high receiving performance is expected inthe Body region and relatively low receiving performance is expected inthe Head and Tail regions.

On the other hand, since the Body region allocates data having highdegree of importance thereto, when the encoding rate of the blockencoder 511 in the first encoder 510 is set lower than that of the blockencoder 5N1 in the second encoder 5N0, data transmission rate is reducedand error correction is increased.

The encoder according to an embodiment of the present invention isconfigured such that the block encoder 511 of the first encoder 510 isimplemented with a 9/10 LDPC having an encoding rate of 9/10, an RScode, etc., and the block encoder 5N1 of the second encoder 5N0 isimplemented with a 1/2 LPDC encoder, 1/2 convolution encoder, etc., eachof which has an encoding rate of 1/2. On the other hand, anotherembodiment modified from the above embodiment can be configured suchthat the block encoder 511 of the first encoder 510 is implemented witha 1/2 LPDC encoder, 1/2 convolution encoder, etc., each of which has anencoding rate of 1/2 and the block encoder 5N1 of the second encoder 5N0is implemented with a 9/10 LDPC having an encoding rate of 9/10, an RScode, etc. Here, such embodiments are just exemplary examples of thepresent invention. Namely, since each block encoder can be implementedwith encoders having different encoding rates, the present inventionwill not limited by such embodiments.

After each encoder performs block coding and block interleavingaccording to types of enhanced data, each byte expansion unit performsbyte expansion. In this case, the number of extended bytes can beidentically or differently set, according to types of inputted enhanceddata and types of data allocated to each region in the data group. Forexample, the high priority enhanced data may be extended by four bytes,and the low priority enhanced data may be extended by two bytes. Also,the enhanced data may be extended by the opposite rates, respectively,or by the same rate. Here, since such expansions can be selectivelydesigned by the inventors, it will be easily appreciated that theycannot limit the scope of the present invention.

The enhanced data, which has undergone byte expansion in each byteexpansion unit, is inputted to the packet formatter 102. Namely, theenhanced data is differently processed by pre-processing according totypes of enhanced data, and then inputted to the packet formatter 102.

The packet formatter 102 allocates the inputted enhanced data to properregions of the Head, Body, and Tail regions in the data group. Forexample, the high priority enhanced data can be allocated in the Bodyregion, and the low priority enhanced data can be allocated to the Headand Tail regions.

Namely, the packet formatter 102 forms data groups, according to typesof the enhanced data, such that the enhanced data can be located to apredetermined place in the Head, Body, and Tail regions after datainterleaving. Also, after predefined known data (or known data placeholder) and an initialization data holder are inserted to a particularplace in the data group according to a particular rule, the result isoutputted to the packet multiplexer 103 on the basis of MPEG packet unitof 188 byte unit.

Block Process

On the other hand, the block processor 113 performs additional encodingfor only enhanced data to output it.

Namely, the block processor 113 outputs its inputs without change, whenthe output of the data interleaver 112 is main data, an MPEG header byteadded in the packet formatter 102, and an RS parity (or an RS parityplace holder) added to the enhanced data packet in the RSencoder/non-systematic RS parity place holder inserter 111.

Also, similar to the main data, the known data (or a known data placeholder) and an initialization data place holder are outputted withoutadditional encoding, but a method for processing the known data may bedifferent from that of the main data.

For example, the packet formatter 102 inserts a known data place holderthereto, and the block processor 113 outputs known data instead of theknown data place holder, in which the known data is generated in theknown data generator 640 in the block processor. Also, the packetformatter 102 inserts known data thereto and then block processor 113outputs its input without additional encoding, similar to the process ofthe main data.

The former method is illustrated in FIG. 8, and the latter method isillustrated in FIG. 9.

Firstly, as shown in FIG. 8, the block processor 113 includes ademultiplexer 610, a buffer 620, an enhanced encoder 630, a known datagenerator 640, and a multiplexer 650.

The enhanced encoder 630 includes a byte-symbol converter 631, a symbolencoder 632, a parallel/serial converter 633, a symbol interleaves 634,and a symbol-byte converter 635.

As shown in FIG. 8, the demultiplexer 610 outputs its output to thebuffer 620 when the inputted data is main data or an RS parity (or an RSparity place holder), and to the enhanced encoder 630 when the inputteddata is enhanced data.

The buffer 620 delays main data and an RS parity (or an RS parity placeholder) for a certain time, and then outputs them to the multiplexer640. Namely, when main data or an RS parity (or an RS parity placeholder) is inputted to the demultiplexer 610, the buffer 620 is used tocompensate time delay which is generated while the enhanced data isadditionally encoded. Afterwards, the main data, whose time differenceis controlled by the buffer 620, is transmitted to the datadeinterleaver 114 through the multiplexer 650.

When the known data is inputted, the known data place holder is insertedthereto in the packet formatter 102. The multiplexer 650 of the blockprocessor 113 selects the training sequence T, which is outputted fromthe known data generator 640, instead of the known data place holder andthen outputs it thereto. Therefore, the known data can be outputtedwithout additional encoding. Here, the initialization data place holder,which is inserted thereto in the packet formatter 102, may be outputtedwithout change, or the known data, which is outputted from the knowndata generator 640, may instead be outputted thereto. In this case, theknown data, which is outputted therefrom instead of the initializationdata place holder, is replaced with an initialization symbol in theTrellis encoding unit 125.

On the other hand, the byte-symbol converter 631 of the enhanced encoder630 converts the enhanced data byte to four symbols and then outputsthem to the symbol encoder 632. The symbol encoder 632 is a G/H encoderwhich encodes G bits of the enhanced data to H bits to output them. Forexample, when 1 bit of the enhanced data is encoded to 2 bits to outputit, G is 1 and H is 2. Also, when 1 bit of the enhance data is encodedto four bits to be outputted, G is 1 and H is 4.

The symbol encoder 632 performs encoding only for bits having effectivedata in the form of input symbols.

For example, assuming that one byte of enhanced data is extended to twobytes as null bits are inserted among the bits in the pre-processor 101.Then, the symbol encoder 632 encodes only effective bits of symbolshaving effective data bits and null bits and then outputs encoded twobits. In this case, the symbol encoder is operated as a 1/2 encoder.

As another embodiment of the present invention, assuming that one byteof enhanced data is extended to four bytes as null bits are insertedamong bits in the pre-processor 101. Then, the symbol encoder 632encodes only effective data bits of two symbols, which is composed bythree null bits and one effective data bit, and then outputs the encodedresult of four bits. Also, as a further embodiment of the presentinvention, the symbol encoder 632 encodes only effective data bits in asymbol composing null bits and effective data bits to generate two bitsand then repeatedly places the encoded two bits, thereby outputting fourbits. In addition, as yet another embodiment of the present invention,from a symbol composing of null bits and effective data bits, effectivedata bits are encoded twice at 1/2 encoding rate to output four bitswhile the encoded symbols are outputted. In these cases, the symbolencoders are operated as a 1/4 encoder.

Namely, the lengths of the enhanced data at the input/output ends of thesymbol encoders 632 are identical to each other. Also, when theeffective data bits are outputted at 1/4 encoding rate, the errorcorrection of 1/4 encoding rate is higher than that of a case whereeffective data bits are outputted at 1/2 encoding rate.

FIG. 10 and FIG. 11 illustrate schematic block diagrams of embodimentsof a symbol encoder 632 according to the present invention.

As shown in FIG. 10, the symbol encoder includes two memories D and anadder, to have four memory states (i.e., 00, 01, 10, 11). The symbolencoder encodes only an effective data bit U among inputs symbols andthen outputs two symbol bits, C1 and C2. Namely, the effective data bitU is outputted as an output upper bit C1, which is not changed from theeffective data bit U, and simultaneously, outputted as an output lowerbit C2 which is generated as the effective data bit U is encoded.

When the pre-processor 101 has performed two byte expansion, the symbolencoder inputs a symbol composed of a null bit X1 and an effective databit U, and then encodes the effective data bit U to output an output bitC1C2.

On the other hand, when the pre-processor 101 has performed four byteexpansion, the symbol encoder inputs two symbols (i.e., four bits),simultaneously, one of which is composed of a null bit and an effectivebit and another of which is composed of two null bits. Afterwards, onlyeffective data bit U among the two symbols U, and X1-X3, is encoded togenerate an output bit C1C2. After that, the output bit C1C2 isrepeatedly placed to generate a final output bit C1C2C1C2 to beoutputted. As another embodiment of the present invention, the symbolencoder encodes only the effective data bit U among the two symbols U,and X1-X2, twice, at 1/2 encoding rate, to generate a final output bitC1C2C1C2 to be outputted. Here, the two symbols are outputted inparallel.

Therefore, the symbol encoder of FIG. 10 may be also operated at a 1/4encoding rate. Here, the X1-X3 are null bits inserted thereto in thepre-processor 101.

As shown in FIG. 11, the symbol encoder includes three memories D andfour adders, such that it can encode only an effective data bit U ofinput symbols to output four bits C1-C4. Namely, the effective data bitU is outputted as an output upper bit C1, which is not changed from theeffective data bit U, and simultaneously, outputted as an output lowerbit C2C3C4 which is generated as the effective data bit U is encoded.

When the pre-processor 101 has performed two byte expansion, only theoutput bit C1C2 is selected on the basis of symbol unit and thenoutputted.

On the other hand, when the pre-processor 101 has performed four byteexpansion, the symbol encoder of FIG. 11 inputs two symbols (i.e., fourbits), simultaneously, one of which is a symbol composed of a null bitand an effective bit and another of which is a symbol composed of twonull bits. After that, only the effective data bit U of the two symbolsU and X1-X3 is encoded to output an output bit C1C2C3C4.

As such, the lengths of enhanced data at the input/output ends of thesymbol encoder 632 are identical to each other, as shown in FIG. 10, andFIG. 11. For example, when the pre-processor 101 has performed two byteexpansion, execution of such process indicates that the null bit and theeffective data bit are composed in the enhanced data at a ratio of 1:1.In this case, one symbol composed of a null bit X1 and an effective databit U is inputted, and only the effective data bit U is encoded tooutput two output bits C1C2. Namely, the input symbol composed of U andX1 is replaced with an output symbol composed of C1 and C2 in the symbolencoder.

Also, when the pre-processor 101 has performed four byte expansion,execution of such process indicates that the null bit and the effectivedata bit are composed in the enhanced data at a ratio of 3:1. In thiscase, two symbols composed of three null bits X1X2X3 and an effectivedata bit U are inputted, and only the effective data bit U is encoded tooutput four output bits C1C2C3C4. Namely, the input symbol composed ofU, X1, X2, and X3 is replaced with an output symbol composed of C1, C2,C3 and C4 in the symbol encoder.

When the symbol encoders of FIG. 10 and FIG. 11 have been operated at a1/2 encoding rate, the outputs of the symbol encoders bypass the rearend of the parallel/serial converter 633 to be inputted to the symbolinterleaver 634. In this case, the parallel/serial converter 633 will beremoved therefrom. Also, when the symbol encoders of FIG. 10 and FIG. 11have been operated at a 1/4 encoding rate, the outputs of the symbolencoders are converted to serial symbols in the rear end of theparallel/serial converter 633 and then inputted to the symbolinterleaver 634.

More specifically, when the symbol encoder is operated at 1/4 encodingrate, it outputs two symbols i.e., four bits, in parallel, and thesymbol interleaver 634 performs interleaving on the basis of symbolunit, i.e., two bit unit. Therefore, the parallel/serial converter 633converts the two symbols inputted in parallel to serial symbols ofsymbol unit to sequentially output the two symbols to the symbolinterleaver 634.

The symbol interleaver 634 inputs the output of the parallel/serialconverter 633 and performs block interleaving therefor on the basis ofsymbol unit.

Here, the symbol interleaver 634 may be implemented with anyinterleavers which can rearrange sequence of interleaved symbols,structurally.

FIG. 8( a) to FIG. 8( c) illustrate diagrams for describing symbolinterleaving according to the present invention, which is performed by avariable length symbol interleaver which can be applicable for symbolshaving various lengths, which have undergone rearrangement of sequencesthereof.

FIG. 8( a) to FIG. 8( c) show symbol interleavings when K=6 and M=8. TheK denotes the number of symbols, which are outputted from theparallel/serial converter 633, to perform symbol interleaving. The M isthe number of symbols which are actually interleaved in the symbolinterleaver 634.

The symbol interleaver 634 of the present invention must satisfy theconditions of M≧K, for M=2^(n). When there is a difference between K andM, an interleaving pattern is formed as null or dummy symbol is addedthereto by the difference (M−K).

Therefore, the K is block size of symbols, which are actually inputtedto the symbol interleaver 634, to perform interleaving, and the M isinterleaving unit for interleaving according to the interleaving patternwhich is generated in the symbol interleaver 634.

FIG. 8( a) to FIG. 8( c) show symbol interleavings when K is 6 and M is8. Therefore, as shown in FIG. 8( a), two symbols have null bits addedthereto to form an interleaving pattern.

The following equation (1) describes a process in which the symbolinterleaver 634 sequentially inputs symbols of K whose sequence will berearranged and obtains M satisfying the conditions of M≧K, for M=2_(n)to form an interleaving pattern, such that the sequence of the symbolscan be rearranged.

P(i)={S×i×(i+1)/2} mod M, for all places  (1)

where M≧K, M=2^(n), and n and S are natural numbers. FIG. 8( a) to FIG.8( c) show interleaving patterns and interleavings therefor, when S=89and M=8.

As shown in FIG. 8( b), the sequence of K input symbols and (M−K) nullsymbols is rearranged on the basis of M symbol unit, using the equation(1). After that, as shown in FIG. 8( c), places of the null symbols areremoved from the symbols of FIG. 8( b), such that the symbols can berearranged using the following equation (2). Afterwards, theinterleaving symbols based on the rearranged sequence are outputted tothe symbol-byte converter 635.

P(i)>K−1, then P(i) is removed/rearranged  (2)

After that, the symbol-byte converter 635 converts the output symbols ofthe symbol interleaver 634 to bytes to output them to the multiplexer650.

The multiplexer 650 selects data outputted from the buffer 620 when theinputted data is main data or an RS parity (or an RS parity placeholder), and enhanced data when the inputted data is the enhanced datawhich is encoded in the enhanced encoder 630 and then outputtedtherefrom. Also, the multiplexer 650 selects training sequence from theknown data generator 635 to output it to the deinterleaver 114, when theinputted data is a known data place holder (or known data).

FIG. 8 and FIG. 9 are identical to each other, except for a known dataprocessing part. Namely, FIG. 9 is identical to FIG. 8 except that, whenthe inputted data is known data, the demultiplexer 660 outputs the knowndata to the buffer 670 such that the buffer 670 can delay a certain timeand then output it to the deinterleaver 114 through the multiplexer 680.Therefore, the detailed description for FIG. 9 will be omitted.

Such processes are performed under the assumption that the known data isalready inserted in the enhanced data packet by the packet formatter102.

FIG. 13 illustrates a schematic block diagram of a demodulating unitincluded a digital broadcast receiving system according to an embodimentof the present invention. Namely, the demodulating unit performsreceiving, modulating, and equalizing for the data transmitted from thedigital broadcast transmitting system, and then restores the originaldata.

More specifically, the demodulating unit includes a demodulator 801, anequalizer 802, a known sequence detector 803, a block decoder 804, adata deinterleaver 805, an RS decoder/non-systematic RS parity remover806, and a derandomizer 807.

Also, the demodulating unit may include a main data packet remover, apacket deformatter 809, and an enhanced data processor 810.

Namely, the received signal through a tuner inputs to the demodulator801 and the known sequence detector 803. The demodulator 801 performsautomatic gain control, carrier recovery and timing recovery, etc., forthe inputted signal to generate a baseband signal, and then output it tothe equalizer 802 and the known sequence detector 803.

The equalizer 802 compensates distortion in the channel included in thedemodulated signal, and then outputs it to the block decoder 804.

Here, the known sequence detector 803 detects known data place, which isinserted in the transmitting end, from input/output data of thedemodulator 801, and then outputs symbol sequence of the known datatogether with information of the known data place, in which the symbolsequence is generated in the known data place, to the demodulator 801,the equalizer 802, and the block decoder 804. Here, the input/outputdata of the demodulator 801 are indicative of data before or afterperforming demodulation. Also, the known sequence detector 803 outputsinformation to the block decoder 804, such that enhanced data, whichperforms additional encoding in the transmitting end, can bediscriminated from the main data, which does not perform additionalencoding, by the block decoder 804 in the receiving end, and such that abeginning point of a block of the enhanced encoder can be identified.

The demodulator 801 enhances its demodulation performance using theknown data symbol sequence when performing timing restoration or carrierrestoration. The equalizer 802 enhances its equalization performanceusing the known data. Also, the equalization performance may be enhancedas the decoding result of the block decoder 804 is feedback to theequalizer 802.

On the other hand, the data, which is inputted to the block decoder 804from the equalizer 802, is main data or enhanced data. Here, the maindata has undergone only Trellis encoding but has not undergoneadditional encoding in the transmitting end, and the enhanced data hasundergone additional encoding and Trellis encoding.

When the inputted data is enhanced data or known data (or known dataplace holder), the block decoder 804 performs Viterbi decoding for theinputted data or hard decision for a soft decision value to output theresult. Also, the transmitting end regards RS parity byte and MPEGheader byte, which are added to the enhanced data packet at thetransmitting end, as main data, and does not perform additional encodingtherefor. Therefore, Viterbi decoding is performed or hard decision isperformed for soft decision value, such that the result can beoutputted.

On the other hand, when the inputted data is enhanced data, the blockdecoder 804 outputs a soft decision value for the inputted enhanceddata. Such a process is performed to enhance performance of additionalerror correction decoding which is performed for the enhanced data inthe enhanced data processor 810.

The enhanced data processor 810 inputs the soft decision value and thenperforms additional error correction decoding therefor. Namely, theenhanced data processor 810 performs error correction decoding for theenhanced data which has undergone soft decision. The error correctiondecoder is implemented with any of an RS decoder, a convolution decoder,a low density parity check code (LDPC) decoder or a turbo decoder for aplurality of decoding periods, etc.

Namely, when the inputted data is enhanced data, the block decoder 804performs decoding for data which is encoded in the block processor 113and the Trellis encoder 203 of the transmitting system. Here, the blockencoder of the pre-processor 101 at the transmitting end is regarded asan outer encoder, and the Trellis encoder 203 of the block processor 113is regarded as an inner encoder.

So that the performance of the outer encoder can be maximized when theadjacent encoded data is decoded, turbo decoding is performed betweendecoder for inner encoded data to output a soft decision value.

Therefore, it is preferable such that the block decoder 804 does notoutput a hard decision value to the enhanced data but a soft decisionvalue.

The block decoder 804 outputs its output to the deinterleaver 805. Thedeinterleaver 805 performs deinterleaving and outputs the deinterleavingresult to the RS decoder/non-systematic RS parity remover 806. Here, thedeinterleaver 805 performs a reverse operation of the data interleaverof the transmitting end. The RS decoder/non-systematic RS parity remover806 performs systematic RS decoding when the inputted packet is maindata packet and removes non-systematic RS parity bytes from the packetwhen the inputted packet is enhanced data packet, to output the resultto the derandomizer 807.

The derandomizer 807 inputs the output of the RS decoder/non-systematicRS parity remover 806 to generate pseudo random byte which is identicalto that of the randomizer of the transmitting system and then performs abitwise exclusive OR (XOR) operation. Afterwards, the derandomizer 807inserts MPEG synchronization byte to each packet and then outputs it onthe basis of 188 byte packet. The output of the derandomizer 807 isoutputted to a main MPEG decoder (not shown) and to the main data packetremover 808, simultaneously. The main MPEG decoder decodes only a packetcorresponding main MPEG. Such processes are performed because theenhanced data packet is not used in the conventional receivers or theenhanced data packet has null or reserved PID, and thus because it isnot decoded in the main MPEG decoder and ignored.

However, it is difficult to perform the XOR operation between the softdecision value of the enhanced data and the pseudo random bit.Therefore, as the data outputted to the main MPEG decoder is describedin detail above, the soft decision value is determined by hard decisionon the basis of sign thereof, and then performs the XOR operation withthe pseudo random bit to output the result. Namely, when the signs ofthe soft decision value are positive and negative, the decision valuesare set to 1 and 0, respectively. Therefore, the decision values performthe XOR operation with a pseudo random bit.

On the other hand, as the enhanced data processor 810 is describedabove, since soft decision is required to enhance its performance whenerror correction code is decoded, the derandomizer 807 generate anadditional output for the enhanced data to output it to the main datapacket remover 808. For example, the derandomizer 807 inverts sign ofthe soft decision value, and then outputs it, when the pseudo random bitis 1. Here, the pseudo random bit performs the XOR operation for thesoft decision value when the enhanced data bit is 1. On the other hand,when the pseudo random bit is 1, the derandomizer 807 outputs it withoutchange.

When the pseudo random bit is 1, the change of sign of the soft decisionvalue is because the data bit outputted from the transmitting system isinverted. Namely, 0⊕1=1 and 1⊕1=0.

In other words, in a case that the pseudo random bit, which is generatedin the derandomizer, is 1, when the pseudo random bit performs an XORoperation with the hard decision value of the enhanced data bit, itsvalue is inverted. Therefore, when the soft decision value is outputtedafter its sign is changed to opposite sign.

The main data packet remover 808 takes only the soft decision value ofthe enhanced data packet from the output of the derandomizer 807 andthen outputs it. Namely, the main data packet remover 808 removes maindata packet of 188 byte unit from the output of the derandomizer 807,and then takes only the soft decision value of the enhanced data packetto output it to the packet deformatter 809.

The packet deformatter 809 removes a MPEG header having PID for enhanceddata from the input data thereof to obtain a packet of 184 byte unit, inwhich the MPEG header is inserted thereto in the transmitting system inorder to be identified with a main data packet. After that, the 184 bytepackets are collected to form a group of a predetermined size, and theknown data, which is inserted thereto in the transmitting system toperform demodulation and equalization, is removed from a predeterminedplace. Afterwards, the Head, Body, Tail regions in the data group areidentified to be outputted to the enhanced data processor 810. Namely,the enhanced data, which has individually undergone pre-process in thepre-processor of the transmitting system, is identified on the basis oftypes and then outputted thereto.

The output of the packet deformatter 809 is inputted to the enhanceddata processor 810.

The enhanced data processor 810 performs block deinterleaving and blockdecoding for the enhanced data which has undergone soft decision.

The enhanced data processor 810 performs a reverse operation of thepre-processor of the transmitting end. The pre-processor of thetransmitting system individually performs block encoding and blockinterleaving for inputted enhanced data according to types of theenhanced data, and byte expansion therefor as null bits are inserted orbits are repeatedly inserted. Then, the enhanced data processor 810performs the reverse operation of the pre-processor of the transmittingend. Namely, the enhanced data processor 810 individually processes theinputted enhanced data according to the types of the enhanced data andthen outputs the enhanced data in a state where the enhanced data isidentified on the basis of importance degree or priority, as theenhanced data is identified on the basis of importance degree orpriority at the transmitting end. Namely, the enhanced data processor810 removes the null bits or repeated bits from the inputted enhanceddata which have undergone soft decision process, on the basis of thetypes thereof. Here, the null bits or repeated bits are used for byteexpansion in the pre-processor. Afterwards, the enhanced data processor810 performs block deinterleaving and block decoding for the removal ofthe null bits and repeated bits to output the finally processed enhanceddata.

For example, the finally processed enhanced data is categorized intohigh priority enhanced data and low priority enhanced data to beoutputted.

FIG. 14 illustrates a schematic block diagram of the block decoder 804of FIG. 13, which performs recurrence turbo decoding for enhanced datawhich has undergone additional encoding at the transmitting end andenhances additional performance thereof.

The block decoder 804 includes a buffer 901, a first multiplexer 902, aTrellis decoding unit 903, a demultiplexer 904, a symbol deinterleaver905, a serial/parallel converter 906, a symbol decoder 907, aparallel/serial converter 908, a symbol interleaver 909, symbol-byteconverters 910 and 912, a hard decision unit 911, and a secondmultiplexer 913.

In order to correspond to the symbol decoder, the symbol interleaver,and the 12-way Trellis encoder, which are included in the transmittingend, the block decoder 804 includes the Trellis decoding unit 903, thesymbol deinterleaver 905, and the symbol decoder 907. Here, the Trellisdecoding unit 903 includes a plurality of 12-way Trellis CodedModulation (TCM) decoders. Therefore, the block decoder 804 performsTrellis decoding, symbol deinterleaving and symbol decoding, which arereverse operations of the transmitting end.

Generally, the turbo decoding is performed such that symbols processedby inner decoder and outer decoder are mapped one to one. On the otherhand, since the present invention is performed such that the main data,known data (or known data place holder), and RS parity (or RS parityplace holder) do not undergo symbol encoding, together with the enhanceddata, but are transmitted thereto, the data must be processed bystructural control in the turbo decoding process.

To this end, when a soft decision value is enhanced data, thedemultiplexer 904 outputs the soft decision value to the symboldeinterleaver 905. Here, the soft decision value undergoes Trellisdecoding in the Trellis decoding unit 903 to be inputted to thedemultiplexer 904. On the other hand, when the soft decision value isone of the main data, known data (or known data place holder), and RSparity (or RS parity place holder), it is converted to a hard decisionvalue through the hard decision unit 911 and then outputted to thesymbol-byte converter 912. The symbol-byte converter 912 converts thehard decision value, which is inputted thereto on the basis of symbolunit, to byte unit to output it to the second multiplexer 913.

Namely, the equalizer 802 outputs its output to the buffer 901 of theblock decoder 804. The buffer 901 outputs its input to the demultiplexer904 through the first multiplexer 902 and the Trellis decoding unit 903,when the inputted data is not enhanced data, or when the inputted datais not one of the main data, known data (or known data place holder) andRS parity (or RS parity place holder).

Also, the buffer 901 stores enhanced data corresponding to one blocksize therein when the inputted data is enhanced data. After that, thebuffer 901 repeatedly outputs the enhanced data to the demultiplexer 904through the first multiplexer 902 and the Trellis decoding unit 903 bythe circulation number while turbo decoding processes are performed.

Here, the block size is identical to the interleaving size K for anactual symbol of the symbol interleaver 634, which is used in FIG. 8 andFIG. 9. The reason the block size and the interleaving size are equal isbecause the turbo decoding is performed between the Trellis decodingunit 903 and the symbol decoder 907.

The Trellis decoding unit 903 performs 12-way Trellis decoding to complywith 12-way Trellis encoding of the transmitting system. The output ofeach 12-way TCM decoder in the Trellis decoding unit 903 is a softdecision value. Here, the soft decision value can be outputted as a loglikelihood ratio (LLR) which is formed as the soft decision value takesa log. The LLR means a log value for a ratio of probabilities whereinput bit will be 1 or 0.

The enhanced data outputted from the demultiplexer 904 is inputted tothe symbol deinterleaver 905 such that it can be processed by symboldeinterleaving, which is a reverse operation of the symbol interleaver634, in the transmitting end. The output of the symbol deinterleaver 905is outputted to the serial/parallel converter 906.

When the enhanced data, which has undergone the symbol deinterleaving,is data which is encoded at 1/4 encoding rate in the transmitting end,the serial/parallel converter 906 outputs its two input symbols to thesymbol decoder 907, simultaneously. Also, when the enhanced data is datawhich is encoded at 1/2 encoding rate in the transmitting end, theserial/parallel converter 906 bypasses its input symbol to the symboldecoder 907 without change. Namely, the outputs of the serial/parallelconverter 906 are changed, according to symbol encoding rate of thesymbol encoder 632, in the transmitting end.

Similarly, the symbol decoder 907 performs symbol decoding, which is areverse operation of the symbol encoder 632, in the transmitting end.

Here, when decoding is completely performed by the circulation number,the output of the symbol decoder 907 is inputted to the symbol-byteconverter 910 to be converted to byte unit. After that, the byte unitdata is inputted to the second multiplexer 913.

On the other hand, if the circulation number for decoding is not yetperformed, the output of the symbol decoder 907 is inputted to theparallel/serial converter 908. When the symbol decoded data is enhanceddata which is decoded at 1/4 encoding rate, the parallel/serialconverter 908 converts the two symbols inputted in parallel to onesymbol unit and then sequentially outputs it. When the symbol decodeddata is enhanced data which is decoded at 1/2 encoding rate, theparallel/serial converter 908 bypasses its input therethrough.

The output of the parallel/serial converter 908 is inputted to thesymbol interleaver 909 and then processed by symbol interleaving of FIG.8, to output the result to the multiplexer 902.

The multiplexer 902 outputs the enhanced data, which is outputted fromthe buffer 901, and the data outputted from the symbol interleaver 909,which has undergone turbo decoding, to corresponding TCM decoders of theTrellis decoding unit 903. Here, the enhanced data and the turbo decodeddata are outputted to each TCM decoder, such that the same places incorresponding blocks of the enhanced data and the turbo decoded data canbe outputted, together. For example, when the turbo decoded data is thethird symbol in the block, it is outputted to a corresponding TCMdecoder together with the third symbol in the block which is stored inthe buffer 901.

The buffer 901 stores corresponding block data while recurrence turbodecoding is being performed, and delays it such that a soft decisionvalue (for example, an LLR) of the output symbol of the symbolinterleaver 909 and the symbol of the buffer 901 can be inputted to theTCM decoder on corresponding way. Here, the symbol of the buffer 901corresponds to the sample place in the block of the output symbol.

After such processes are performed while the turbo decoding isrepeatedly performed for the predetermined number of times, next blockdata is inputted to the buffer 901 to repeat the turbo decoding.

Namely, when the turbo decoding has been performed by the predeterminednumber of times, the output of the symbol decoder 907 is converted to asoft decision value of byte unit in the symbol-byte converter 910 andthen outputted to the second multiplexer 913. Therefore, the blockdecoding process for one block is completed. Such processes are referredto as recurrence turbo decoding for convenience of description of thepresent invention.

Here, the number of recurrence turbo decoding can be defined in relationto the Trellis decoding unit 903 and the symbol decoder 907, consideringhardware complexity and error correction performance. When the number isincreased, the error correction is better but the hardware is somewhatcomplicated.

AS such, as the recurrence turbo decoding algorithm, as shown in FIG.14, is performed for a plurality of decoding periods in which the symboldecoding for the enhanced data uses a Soft-Out Viterbi Algorithm (SOVA)algorithm and a Maximum A posteriori Probability (MAP) algorithm, etc.,the present invention can additionally enhance total decodingperformance thereof.

FIG. 15 illustrates a block diagram showing the structure of atransmitting system according to an embodiment of the present invention.The digital broadcast transmitting system includes a pre-processor 1110,a packet multiplexer 1121, a data randomizer 1122, a Reed-Solomon (RS)encoder/non-systematic RS encoder 1123, a data interleaves 1124, aparity byte replacer 1125, a non-systematic RS encoder 1126, a trellisencoding module 1127, a frame multiplexer 1128, and a transmitting unit1130. The pre-processor 1110 includes an enhanced data randomizer 1111,a RS frame encoder 1112, a block processor 1113, a group formatter 1114,a data deinterleaver 1115, and a packet formatter 1116.

In the present invention having the above-described structure, main dataare inputted to the packet multiplexer 1121. Enhanced data are inputtedto the enhanced data randomizer 1111 of the pre-processor 1110, whereinan additional coding process is performed so that the present inventioncan respond swiftly and appropriately against noise and change inchannel. The enhanced data randomizer 1111 randomizes the receivedenhanced data and outputs the randomized enhanced data to the RS frameencoder 1112. At this point, by having the enhanced data randomizer 1111perform the randomizing process on the enhanced data, the randomizingprocess on the enhanced data by the data randomizer 1122 in a laterprocess may be omitted. Either the randomizer of the conventionalbroadcast system may be used as the randomizer for randomizing theenhanced data, or any other type of randomizer may be used herein.

The RS frame encoder 1112 receives the randomized enhanced data andperforms at least one of an error correction coding process and an errordetection coding process on the received data. Accordingly, by providingrobustness to the enhanced data, the data can scatter group error thatmay occur due to a change in the frequency environment. Thus, the datacan respond appropriately to the frequency environment which is verypoor and liable to change. The RS frame multiplexer 1112 also includes aprocess of mixing in row units many sets of enhanced data each having apre-determined size. By performing an error correction coding process onthe inputted enhanced data, the RS frame encoder 1112 adds data requiredfor the error correction and, then, performs an error detection codingprocess, thereby adding data required for the error detection process.The error correction coding uses the RS coding method, and the errordetection coding uses the cyclic redundancy check (CRC) coding method.When performing the RS coding process, parity data required for theerror correction are generated. And, when performing the CRC codingprocess, CRC data required for the error detection are generated.

The RS frame encoder 1112 performs CRC coding on the RS coded enhanceddata in order to create the CRC code. The CRC code that is generated bythe CRC coding process may be used to indicate whether the enhanced datahave been damaged by an error while being transmitted through thechannel. The present invention may adopt other types of error detectioncoding methods, apart from the CRC coding method, and may also use theerror correction coding method so as to enhance the overall errorcorrection ability of the receiving system. For example, assuming thatthe size of one RS frame is 187*N bytes, that (235,187)-RS codingprocess is performed on each column within the RS frame, and that a CRCcoding process using a 2-byte (i.e., 16-bit) CRC checksum, then a RSframe having the size of 187*N bytes is expanded to a RS frame of235*(N+2) bytes. The RS frame expanded by the RS frame encoder 1112 isinputted to the block processor 1113. The block processor 1113 codes theRS-coded and CRC-coded enhanced data at a coding rate of G/H. Then, theblock processor 1113 outputs the G/H-rate coded enhanced data to thegroup formatter 1114. In order to do so, the block processor 1113identifies the block data bytes being inputted from the RS frame encoder1112 as bits.

The block processor 1113 may receive supplemental information data suchas signaling information, which include information on the system, andidentifies the supplemental information data bytes as data bits. Herein,the supplemental information data, such as the signaling information,may equally pass through the enhanced data randomizer 1111 and the RSframe encoder 1112 so as to be inputted to the block processor 1113.Alternatively, the supplemental information data may be directlyinputted to the block processor 1113 without passing through theenhanced data randomizer 1111 and the RS frame encoder 1112. Thesignaling information corresponds to information required for receivingand processing data included in the data group in the receiving system.Such signaling information includes data group information, multiplexinginformation, and burst information.

As a G/H-rate encoder, the block processor 1113 codes the inputted dataat a coding rate of G/H and then outputs the G/H-rate coded data. Forexample, if 1 bit of the input data is coded to 2 bits and outputted,then G is equal to 1 and H is equal to 2 (i.e., G=1 and H=2).Alternatively, if 1 bit of the input data is coded to 4 bits andoutputted, then G is equal to 1 and H is equal to 4 (i.e., G=1 and H=4).As an example of the present invention, it is assumed that the blockprocessor 1113 performs a coding process at a coding rate of 1/2 (alsoreferred to as a 1/2-rate coding process) or a coding process at acoding rate of 1/4 (also referred to as a 1/4-rate coding process). Morespecifically, the block processor 1113 codes the received enhanced dataand supplemental information data, such as the signaling information, ateither a coding rate of 1/2 or a coding rate of 1/4. Thereafter, thesupplemental information data, such as the signaling information, areidentified and processed as enhanced data.

Since the 1/4-rate coding process has a higher coding rate than the1/2-rate coding process, greater error correction ability may beprovided. Therefore, in a later process, by allocating the 1/4-ratecoded data in an area with deficient receiving performance within thegroup formatter 1114, and by allocating the 1/2-rate coded data in anarea with excellent receiving performance, the difference in the overallperformance may be reduced. More specifically, in case of performing the1/2-rate coding process, the block processor 1113 receives 1 bit andcodes the received 1 bit to bits (i.e., 1 symbol). Then, the blockprocessor 1113 outputs the processed 2 bits (or 1 symbol). On the otherhand, in case of performing the 1/4-rate coding process, the blockprocessor 1113 receives 1 bit and codes the received 1 bit to 4 bits(i.e., 2 symbols). Then, the block processor 1113 outputs the processed4 bits (or 2 symbols). Additionally, the block processor 1113 performs ablock interleaving process in symbol units on the symbol-coded data.Subsequently, the block processor 1113 converts to bytes the datasymbols that are block-interleaved and have the order rearranged.

The group formatter 1114 inserts the enhanced data outputted from theblock processor 1113 (herein, the enhanced data may include supplementalinformation data such as signaling information including transmissioninformation) in a corresponding area within the data group, which isconfigured according to a pre-defined rule. Furthermore, in relationwith the data deinterleaving process, various types of places holders orknown data are also inserted in corresponding areas within the datagroup.

At this point, the data group may be described by at least onehierarchical area. Herein, the data allocated to the each area may varydepending upon the characteristic of each hierarchical area.Additionally, each group is configured to include a fieldsynchronization signal.

In another example given in the present invention, a data group isdivided into FIRST, SECOND, and THIRD regions in a data configurationprior to data deinterleaving.

FIG. 16A illustrates an alignment of data before being data interleavedand identified, and FIG. 16B illustrates an alignment of data afterbeing data interleaved and identified. More specifically, a datastructure identical to that shown in FIG. 16B is transmitted to areceiving system. Also, the data group configured to have the samestructure as the data structure shown in FIG. 16B is inputted to thedata deinterleaver 1115.

As described above, FIG. 16A illustrates a data structure prior to datainterleaving that is divided into 3 regions, such as region FIRST,region SECOND, and region THIRD. Also, in the present invention, each ofthe regions FIRST to THIRD is further divided into a plurality ofregions. Referring to FIG. 16B, region FIRST is divided into 5 regions(FI1 to FI5), region SECOND is divided into 2 regions (SE1 and SE2), andregion THIRD is divided into 3 regions (TH1 to TH3). Herein, regionsFIRST to THIRD are identified as regions having similar receivingperformances within the data group. Herein, the type of enhanced data,which are inputted, may also vary depending upon the characteristic ofeach region.

In the example of the present invention, the data structure is dividedinto regions FIRST to THIRD based upon the level of interference of themain data. Herein, the data group is divided into a plurality of regionsto be used for different purposes. More specifically, a region of themain data having no interference or a very low interference level may beconsidered to have a more resistant (or stronger) receiving performanceas compared to regions having higher interference levels. Additionally,when using a system inserting and transmitting known data in the datagroup, and when consecutively long known data are to be periodicallyinserted in the enhanced data, the known data having a predeterminedlength may be periodically inserted in the region having no interferencefrom the main data (e.g., region FIRST). However, due to interferencefrom the main data, it is difficult to periodically insert known dataand also to insert consecutively long known data to a region havinginterference from the main data (e.g., region SECOND and region THIRD).

Hereinafter, examples of allocating data to region FIRST (FI1 to FI5),region SECOND (SE1 and SE2), and region THIRD (TH1 to TH3) will now bedescribed in detail with reference to FIG. 16B. The data group size, thenumber of hierarchically divided regions within the data group and thesize of each region, and the number of enhanced data bytes that can beinserted in each hierarchically divided region of FIG. 16B are merelyexamples given to facilitate the understanding of the present invention.Herein, the group formatter 1114 creates a data group including placesin which field synchronization bytes are to be inserted, so as to createthe data group that will hereinafter be described in detail.

More specifically, region FIRST is a region within the data group inwhich a long known data sequence may be periodically inserted, and inwhich includes regions wherein the main data are not mixed (e.g., FI1 toFI5). Also, region FIRST includes a region (e.g., FI1) located between afield synchronization region and the region in which the first knowndata sequence is to be inserted. The field synchronization region hasthe length of one segment (i.e., 832 symbols) existing in an ATSCsystem.

For example, referring to FIG. 16B, 2428 bytes of the enhanced data maybe inserted in region FI1, 2580 bytes may be inserted in region FI2,2772 bytes may be inserted in region FI3, 2472 bytes may be inserted inregion FI4, and 2772 bytes may be inserted in region FI5. Herein,trellis initialization data or known data, MPEG header, and RS parityare not included in the enhanced data. As described above, when regionFIRST includes a known data sequence at both ends, the receiving systemuses channel information that can obtain known data or fieldsynchronization data, so as to perform equalization, thereby providingenforced equalization performance.

Also, region SECOND includes a region located within 8 segments at thebeginning of a field synchronization region within the data group(chronologically placed before region FI1) (e.g., region SE1), and aregion located within 8 segments behind the very last known datasequence which is inserted in the data group (e.g., region SE2). Forexample, 930 bytes of the enhanced data may be inserted in the regionSE1, and 1350 bytes may be inserted in region SE2. Similarly, trellisinitialization data or known data, MPEG header, and RS parity are notincluded in the enhanced data. In case of region SECOND, the receivingsystem may perform equalization by using channel information obtainedfrom the field synchronization section. Alternatively, the receivingsystem may also perform equalization by using channel information thatmay be obtained from the last known data sequence, thereby enabling thesystem to respond to the channel changes.

Region THIRD includes a region located within 30 segments including andpreceding the 9^(th) segment of the field synchronization region(chronologically located before region FIRST) (e.g., region TH1), aregion located within 12 segments including and following the 9^(th)segment of the very last known data sequence within the data group(chronologically located after region FIRST) (e.g., region TH2), and aregion located in 32 segments after the region TH2 (e.g., region TH3).For example, 1272 bytes of the enhanced data may be inserted in theregion TH1, 1560 bytes may be inserted in region TH2, and 1312 bytes maybe inserted in region TH3. Similarly, trellis initialization data orknown data, MPEG header, and RS parity are not included in the enhanceddata. Herein, region THIRD (e.g., region TH1) is located chronologicallyearlier than (or before) region FIRST.

Since region THIRD (e.g., region TH1) is located further apart from thefield synchronization region which corresponds to the closest known dataregion, the receiving system may use the channel information obtainedfrom the field synchronization data when performing channelequalization. Alternatively, the receiving system may also use the mostrecent channel information of a previous data group. Furthermore, inregion THIRD (e.g., region TH2 and region TH3) located before regionFIRST, the receiving system may use the channel information obtainedfrom the last known data sequence to perform equalization. However, whenthe channels are subject to fast and frequent changes, the equalizationmay not be performed perfectly. Therefore, the equalization performanceof region THIRD may be deteriorated as compared to that of regionSECOND.

When it is assumed that the data group is allocated with a plurality ofhierarchically divided regions, as described above, the block processor1113 may encode the enhanced data, which are to be inserted to eachregion based upon the characteristic of each hierarchical region, at adifferent coding rate. For example, the block processor 1113 may encodethe enhanced data, which are to be inserted in regions FI1 to F15 ofregion FIRST, at a coding rate of 1/2. Then, the group formatter 1114may insert the 1/2-rate encoded enhanced data to regions FI1 to FI5.

The block processor 1113 may encode the enhanced data, which are to beinserted in regions SE1 and SE2 of region SECOND, at a coding rate of1/4 having higher error correction ability as compared to the 1/2-codingrate. Then, the group formatter 1114 inserts the 1/4-rate coded enhanceddata in region SE1 and region SE2. Furthermore, the block processor 1113may encode the enhanced data, which are to be inserted in regions TH1 toTH3 of region THIRD, at a coding rate of 1/4 or a coding rate havinghigher error correction ability than the 1/4-coding rate. Then, thegroup formatter 1114 may either insert the encoded enhanced data toregions TH1 to TH3, as described above, or leave the data in a reservedregion for future usage.

In addition, the group formatter 1114 also inserts supplemental data,such as signaling information that notifies the overall transmissioninformation, other than the enhanced data in the data group. Also, apartfrom the encoded enhanced data outputted from the block processor 1113,the group formatter 1114 also inserts MPEG header place holders,non-systematic RS parity place holders, main data place holders, whichare related to data deinterleaving in a later process, as shown in FIG.16A. Herein, the main data place holders are inserted because theenhanced data bytes and the main data bytes are alternately mixed withone another in regions SECOND and THIRD based upon the input of the datadeinterleaver, as shown in FIG. 16A. For example, based upon the dataoutputted after data deinterleaving, the place holder for the MPEGheader may be allocated at the very beginning of each packet.

Furthermore, the group formatter 1114 either inserts known datagenerated in accordance with a pre-determined method or inserts knowndata place holders for inserting the known data in a later process.Additionally, place holders for initializing the trellis encoder 1127are also inserted in the corresponding regions. For example, theinitialization data place holders may be inserted in the beginning ofthe known data sequence. Herein, the size of the enhanced data that canbe inserted in a data group may vary in accordance with the sizes of thetrellis initialization place holders or known data (or known data placeholders), MPEG header place holders, and RS parity place holders.

The output of the group formatter 1114 is inputted to the datadeinterleaver 1115. And, the data deinterleaver 1115 deinterleaves databy performing an inverse process of the data interleaves on the data andplace holders within the data group, which are then outputted to thepacket formatter 1116. More specifically, when the data and placeholders within the data group configured, as shown in FIG. 16A, aredeinterleaved by the data deinterleaver 1115, the data group beingoutputted to the packet formatter 1116 is configured to have thestructure shown in FIG. 16B.

Among the data deinterleaved and inputted, the packet formatter 1116removes the main data place holder and RS parity place holder that wereallocated for the deinterleaving process from the inputted deinterleaveddata. Thereafter, the remaining portion of the corresponding data isgrouped, and 4 bytes of MPEG header are inserted therein. The 4-byteMPEG header is configured of a 1-byte MPEG synchronization byte added tothe 3-byte MPEG header place holder.

When the group formatter 1114 inserts the known data place holder, thepacket formatter 1116 may either insert actual known data in the knowndata place holder or output the known data place holder without anychange or modification for a replacement insertion in a later process.Afterwards, the packet formatter 1116 divides the data within theabove-described packet-formatted data group into 188-byte unit enhanceddata packets (i.e., MPEG TS packets), which are then provided to thepacket multiplexer 1121. The packet multiplexer 1121 multiplexes the188-byte unit enhanced data packet and main data packet outputted fromthe packet formatter 1116 according to a pre-defined multiplexingmethod. Subsequently, the multiplexed data packets are outputted to thedata randomizer 1122. The multiplexing method may be modified or alteredin accordance with diverse variables of the system design.

As an example of the multiplexing method of the packet multiplexer 1121,the enhanced data burst section and the main data section may beidentified along a time axis (or a chronological axis) and may bealternately repeated. At this point, the enhanced data burst section maytransmit at least one data group, and the main data section may transmitonly the main data. The enhanced data burst section may also transmitthe main data. If the enhanced data are outputted in a burst structure,as described above, the receiving system receiving only the enhanceddata may turn the power on only during the burst section so as toreceive the enhanced data, and may turn the power off during the maindata section in which main data are transmitted, so as to prevent themain data from being received, thereby reducing the power consumption ofthe receiving system.

When the data being inputted correspond to the main data packet, thedata randomizer 1122 performs the same randomizing process of theconventional randomizer. More specifically, the MPEG synchronizationbyte included in the main data packet is discarded and a pseudo randombyte generated from the remaining 187 bytes is used so as to randomizethe data. Thereafter, the randomized data are outputted to the RSencoder/non-systematic RS encoder 1123. However, when the inputted datacorrespond to the enhanced data packet, the MPEG synchronization byte ofthe 4-byte MPEG header included in the enhanced data packet isdiscarded, and data randomizing is performed only on the remaining3-byte MPEG header. Randomizing is not performed on the remainingportion of the enhanced data. Instead, the remaining portion of theenhanced data is outputted to the RS encoder/non-systematic RS encoder1123. This is because the randomizing process has already been performedon the enhanced data by the enhanced data randomizer 1111 in an earlierprocess. Herein, a data randomizing process may or may not be performedon the known data (or known data place holder) and the initializationdata place holder included in the enhanced data packet.

The RS encoder/non-systematic RS encoder 1123 RS-codes the datarandomized by the data randomizer 1122 or the data bypassing the datarandomizer 1122. Then, the RS encoder/non-systematic RS encoder 1123adds a 20-byte RS parity to the coded data, thereby outputting theRS-parity-added data to the data interleaver 1124. At this point, if theinputted data correspond to the main data packet, the RSencoder/non-systematic RS encoder 1123 performs a systematic RS-codingprocess identical to that of the conventional receiving system on theinputted data, thereby adding the 20-byte RS parity at the end of the187-byte data. Alternatively, if the inputted data correspond to theenhanced data packet, the 20 bytes of RS parity gained by performing thenon-systematic RS-coding are respectively inserted in the decided paritybyte places within the enhanced data packet. Herein, the datainterleaver 1124 corresponds to a byte unit convolutional interleaver.The output of the data interleaver 1124 is inputted to the parity bytereplacer 1125 and the non-systematic RS encoder 1126.

Meanwhile, a memory within the trellis encoding module 1127, which ispositioned after the parity byte replacer 1125, should first beinitialized in order to allow the output data of the trellis encodingmodule 1127 so as to become the known data defined based upon anagreement between the receiving system and the transmitting system. Morespecifically, the memory of the trellis encoding module 1127 shouldfirst be initialized before the known data sequence being inputted istrellis-encoded. At this point, the beginning of the known data sequencethat is inputted corresponds to the initialization data place holderinserted by the group formatter 1114 and not the actual known data.Therefore, a process of generating initialization data right before thetrellis-encoding of the known data sequence being inputted and a processof replacing the initialization data place holder of the correspondingtrellis encoding module memory with the newly generated initializationdata are required.

A value of the trellis memory initialization data is decided based uponthe memory status of the trellis encoding module 1127, therebygenerating the trellis memory initialization data accordingly. Due tothe influence of the replace initialization data, a process ofrecalculating the RS parity, thereby replacing the RS parity outputtedfrom the trellis encoding module 1127 with the newly calculated RSparity is required. Accordingly, the non-systematic RS encoder 1126receives the enhanced data packet including the initialization dataplace holder that is to be replaced with the initialization data fromthe data interleaver 1124 and also receives the initialization data fromthe trellis encoding module 1127. Thereafter, among the receivedenhanced data packet, the initialization data place holder is replacedwith the initialization data. Subsequently, the RS parity data added tothe enhanced data packet are removed. Then, a new non-systematic RSparity is calculated and outputted to the parity byte replacer 1125.Accordingly, the parity byte replacer 1125 selects the output of thedata interleaver 1124 as the data within the enhanced data packet, andselects the output of the non-systematic RS encoder 1126 as the RSparity. Thereafter, the parity byte replacer 1125 outputs the selecteddata.

Meanwhile, if the main data packet is inputted, or if the enhanced datapacket that does not include the initialization data place holder thatis to be replaced, the parity byte replacer 1125 selects the data and RSparity outputted from the data interleaver 1124 and directly outputs theselected data to the trellis encoding module 1127 without modification.The trellis encoding module 1127 converts the byte-unit data tosymbol-unit data and 12-way interleaves and trellis-encodes theconverted data, which are then outputted to the frame multiplexer 1128.The frame multiplexer 1128 inserts field synchronization and segmentsynchronization signals in the output of the trellis encoding module1127 and then outputs the processed data to the transmitting unit 1130.Herein, the transmitting unit 1130 includes a pilot inserter 1131, amodulator 1132, and a radio frequency (RF) up-converter 1133. Theoperation of the transmitting unit 1130 is identical to the conventionaltransmitters. Therefore, a detailed description of the same will beomitted for simplicity.

FIG. 17 illustrates a block diagram of a demodulating unit included inthe receiving system according to another embodiment of the presentinvention. Herein, the demodulating unit may effectively process signalstransmitted from the transmitting system shown in FIG. 15. Referring toFIG. 17, the demodulating unit includes a demodulator 2001, a channelequalizer 2002, a known sequence detector 2003, a block decoder 2004, anenhanced data deformatter 2005, a RS frame decoder 2006, an enhanceddata derandomizer 2007, a data deinterleaver 2008, a RS decoder 2009,and a main data derandomizer 2010. More specifically, the enhanced dataincluding known data and the main data are received through the tunerand inputted to the demodulator 2001 and the known sequence detector2003. The demodulator 2001 performs automatic gain control, carrier waverecovery, and timing recovery on the data that are being inputted,thereby creating baseband data, which are then outputted to theequalizer 2002 and the known sequence detector 2003. The equalizer 2002compensates the distortion within the channel included in thedemodulated data. Then, the equalizer 2002 outputs the compensated datato the block decoder 2004.

At this point, the known sequence detector 2003 detects the known dataplace inserted by the transmitting system to the input/output data ofthe demodulator 2001 (i.e., data prior to demodulation or data afterdemodulation). Then, along with the position information, the knownsequence detector 2003 outputs the symbol sequence of the known datagenerated from the corresponding position to the demodulator 2001 andthe equalizer 2002. Additionally, the known sequence detector 2003outputs information enabling the block decoder 2004 to identify theenhanced data being additionally encoded by the transmitting system andthe main data that are not additionally encoded to the block decoder2004. Furthermore, although the connection is not shown in FIG. 17, theinformation detected by the known sequence detector 2003 may be used inthe overall receiving system and may also be used in the enhanced dataformatter 2005 and the RS frame decoder 2006.

By using the known data symbol sequence when performing the timingrecovery or carrier wave recovery, the demodulating performance of thedemodulator 2001 may be enhanced. Similarly, by using the known data,the channel equalizing performance of the channel equalizer 2002 may beenhanced. Furthermore, by feeding-back the decoding result of the blockdecoder 2004 to the channel equalizer 2002, the channel equalizingperformance may also be enhanced.

The channel equalizer 2002 may perform channel equalization by using aplurality of methods. An example of estimating a channel impulseresponse (CIR) so as to perform channel equalization will be given inthe description of the present invention. Most particularly, an exampleof estimating the CIR in accordance with each region within the datagroup, which is hierarchically divided and transmitted from thetransmitting system, and applying each CIR differently will also bedescribed herein. Furthermore, by using the known data, the place andcontents of which is known in accordance with an agreement between thetransmitting system and the receiving system, and the fieldsynchronization data, so as to estimate the CIR, the present inventionmay be able to perform channel equalization with more stability.

Herein, the data group that is inputted for the equalization process isdivided into regions FIRST to THIRD, as shown in FIG. 16B. Morespecifically, in the example of the present invention, each regionFIRST, SECOND, and THIRD are further divided into regions FI1 to FI5,regions SE1 and SE2, and regions TH1 to TH3, respectively. Referring toFIG. 16B, the CIR that is estimated from the field synchronization datain the data structure is referred to as CIR_FS. Alternatively, the CIRsthat are estimated from each of the 5 known data sequences existing inregion FIRST are sequentially referred to as CIR_N0, CIR_N1, CIR_N2,CIR_N3, and CIR_N4.

As described above, the present invention uses the CIR estimated fromthe field synchronization data and the known data sequences in order toperform channel equalization on data within the data group. At thispoint, each of the estimated CIRs may be directly used in accordancewith the characteristics of each region within the data group.Alternatively, a plurality of the estimated CIRs may also be eitherinterpolated or extrapolated so as to create a new CIR, which is thenused for the channel equalization process.

Herein, when a value F(Q) of a function F(x) at a particular point Q anda value F(S) of the function F(x) at another particular point S areknown, interpolation refers to estimating a function value of a pointwithin the section between points Q and S. Linear interpolationcorresponds to the simplest form among a wide range of interpolationoperations. The linear interpolation described herein is merelyexemplary among a wide range of possible interpolation methods. And,therefore, the present invention is not limited only to the examples setforth herein.

Alternatively, when a value F(Q) of a function F(x) at a particularpoint Q and a value F(S) of the function F(x) at another particularpoint S are known, extrapolation refers to estimating a function valueof a point outside of the section between points Q and S. Linearextrapolation is the simplest form among a wide range of extrapolationoperations. Similarly, the linear extrapolation described herein ismerely exemplary among a wide range of possible extrapolation methods.And, therefore, the present invention is not limited only to theexamples set forth herein.

More specifically, in case of region TH1, any one of the CIR_N4estimated from a previous data group, the CIR_FS estimated from thecurrent data group that is to be processed with channel equalization,and a new CIR generated by extrapolating the CIR_FS of the current datagroup and the CIR_N0 may be used to perform channel equalization.Alternatively, in case of region SE1, a variety of methods may beapplied as described in the case for region TH1. For example, a new CIRcreated by linearly extrapolating the CIR_FS estimated from the currentdata group and the CIR_N0 may be used to perform channel equalization.Also, the CIR_FS estimated from the current data group may also be usedto perform channel equalization. Finally, in case of region FI1, a newCIR may be created by interpolating the CIR_FS estimated from thecurrent data group and CIR_N0, which is then used to perform channelequalization. Furthermore, any one of the CIR_FS estimated from thecurrent data group and CIR_N0 may be used to perform channelequalization.

In case of regions FI2 to FI5, CIR_N(i−1) estimated from the currentdata group and CIR_N(i) may be interpolated to create a new CIR and usethe newly created CIR to perform channel equalization. Also, any one ofthe CIR_N(i−1) estimated from the current data group and the CIR_N(i)may be used to perform channel equalization. Alternatively, in case ofregions SE2, TH2, and TH3, CTR_N3 and CIR_N4 both estimated from thecurrent data group may be extrapolated to create a new CIR, which isthen used to perform the channel equalization process. Furthermore, theCIR_N4 estimated from the current data group may be used to perform thechannel equalization process. Accordingly, an optimum performance may beobtained when performing channel equalization on the data inserted inthe data group. The methods of obtaining the CIRs required forperforming the channel equalization process in each region within thedata group, as described above, are merely examples given to facilitatethe understanding of the present invention. A wider range of methods mayalso be used herein. And, therefore, the present invention will not onlybe limited to the examples given in the description set forth herein.

Meanwhile, if the data being channel equalized and then inputted to theblock decoder 2004 correspond to the enhanced data on which additionalencoding and trellis encoding are both performed by the transmittingsystem, trellis-decoding and additional decoding processes are performedas inverse processes of the transmitting system. Alternatively, if thedata being channel equalized and then inputted to the block decoder 2004correspond to the main data on which additional encoding is notperformed and only trellis-encoding is performed by the transmittingsystem, only the trellis-decoding process is performed. The data groupdecoded by the block decoder 2004 is inputted to the enhanced datadeformatter 2005, and the main data packet is inputted to the datadeinterleaver 2008.

More specifically, if the inputted data correspond to the main data, theblock decoder 2004 performs Viterbi decoding on the inputted data, so asto either output a hard decision value or hard-decide a soft decisionvalue and output the hard-decided result. On the other hand, if theinputted correspond to the enhanced data, the block decoder 2004 outputseither a hard decision value or a soft decision value on the inputtedenhanced data. In other words, if the data inputted to the block decoder2004 correspond to the enhanced data, the block decoder 2004 performs adecoding process on the data encoded by the block processor and thetrellis encoder of the transmitting system. At this point, the output ofthe RS frame encoder included in the pre-processor of the transmittingsystem becomes an external code, and the output of the block processorand the trellis encoder becomes an internal code. In order to showmaximum performance of the external code when decoding such connectioncodes, the decoder of the internal code should output a soft decisionvalue. Therefore, the block decoder 2004 may output a hard decisionvalue on the enhanced data. However, when required, it is morepreferable that the block decoder 2004 outputs a soft decision value.

The present invention may also be used for configuring a reliability mapusing the soft decision value. The reliability map determines andindicates whether a byte corresponding to a group of 8 bits decided bythe code of the soft decision value is reliable. For example, when anabsolute value of the soft decision value exceeds a pre-determinedthreshold value, the value of the bit corresponding to the soft decisionvalue code is determined to be reliable. However, if the absolute valuedoes not exceed the pre-determined threshold value, then the value ofthe corresponding bit is determined to be not reliable. Further, if atleast one bit among the group of 8 bits, which are determined based uponthe soft decision value, is determined to be not reliable, then thereliability map indicates that the entire byte is not reliable. Herein,the process of determining the reliability by 1-bit units is merelyexemplary. The corresponding byte may also be indicated to be notreliable if a plurality of bits (e.g., 4 bits) is determined to be notreliable.

Conversely, when all of the bits are determined to be reliable withinone byte (i.e., when the absolute value of the soft value of all bitsexceeds the pre-determined threshold value), then the reliability mapdetermines and indicates that the corresponding data byte is reliable.Similarly, when more than 4 bits are determined to be reliable withinone data byte, then the reliability map determines and indicates thatthe corresponding data byte is reliable. The estimated numbers aremerely exemplary and do not limit the scope and spirit of the presentinvention. Herein, the reliability map may be used when performing errorcorrection decoding processes.

Meanwhile, the data deinterleaver 2008, the RS decoder 2009, and themain data derandomizer 2010 are blocks required for receiving the maindata. These blocks may not be required in a receiving system structurethat receives only the enhanced data. The data deinterleaver 2008performs an inverse process of the data interleaver of the transmittingsystem. More specifically, the data deinterleaver 2008 deinterleaves themain data being outputted from the block decoder 2004 and outputs thedeinterleaved data to the RS decoder 2009. The RS decoder 2009 performssystematic RS decoding on the deinterleaved data and outputs thesystematically decoded data to the main data derandomizer 2010. The maindata derandomizer 2010 receives the data outputted from the RS decoder2009 so as to generate the same pseudo random byte as that of therandomizer in the transmitting system. The main data derandomizer 2010then performs a bitwise exclusive OR (XOR) operation on the generatedpseudo random data byte, thereby inserting the MPEG synchronizationbytes to the beginning of each packet so as to output the data in188-byte main data packet units.

Herein, the format of the data being outputted to the enhanced datadeformatter 2005 from the block decoder 2004 is a data group format. Atthis point, the enhanced data deformatter 2005 already knows thestructure of the input data. Therefore, the enhanced data deformatter2005 identifies the system information including signaling informationand the enhanced data from the data group. Thereafter, the identifiedsignaling information is transmitted to where the system information isrequired, and the enhanced data are outputted to the RS frame decoder2006. The enhanced data deformatter 2005 removes the known data, trellisinitialization data, and MPEG header that were included in the main dataand the data group and also removes the RS parity that was added by theRS encoder/non-systematic RS encoder of the transmitting system.Thereafter, the processed data are outputted to the RS frame decoder2006.

More specifically, the RS frame decoder 2006 receives the RS-coded andCRC-coded enhanced data from the enhanced data deformatter 2005 so as toconfigure the RS frame. The RS frame decoder 2006 performs an inverseprocess of the RS frame encoder included in the transmitting system,thereby correcting the errors within the RS frame. Then, the 1-byte MPEGsynchronization byte, which was removed during the RS frame codingprocess, is added to the error corrected enhanced data packet.Subsequently, the processed data are outputted to the enhanced dataderandomizer 2007. Herein, the enhanced data derandomizer 2007 performsa derandomizing process, which corresponds to an inverse process of theenhanced data randomizer included in the transmitting system, on thereceived enhanced data. Then, by outputting the processed data, theenhanced data transmitted from the transmitting system can be obtained.

According to an embodiment of the present invention, the RS framedecoder 2006 may also be configured as follows. The RS frame decoder2006 may perform a CRC syndrome check on the RS frame, thereby verifyingwhether or not an error has occurred in each row. Subsequently, the CRCchecksum is removed and the presence of an error is indicated on a CRCerror flag corresponding to each row. Then, a RS decoding process isperformed on the RS frame having the CRC checksum removed in a columndirection. At this point, depending upon the number of CRC error flags,a RS erasure decoding process may be performed. More specifically, bychecking the CRC error flags corresponding to each row within the RSframe, the number of CRC error flags may be determined whether it isgreater or smaller than the maximum number of errors, when RS decodingthe number of rows with errors (or erroneous rows) in the columndirection. Herein, the maximum number of errors corresponds to thenumber of parity bytes inserted during the RS decoding process. As anexample of the present invention, it is assumed that 48 parity bytes areadded to each column.

If the number of rows with CRC errors is equal to or smaller than themaximum number of errors (e.g., 48), which may be corrected by the RSerasure decoding process, the RS erasure decoding process is performedon the RS frame in the column direction. Thereafter, the 48 bytes ofparity data that were added at the end of each column are removed.However, if the number of rows with CRC errors is greater than themaximum number of errors (e.g., 48), which may be corrected by the RSerasure decoding process, the RS erasure decoding process cannot beperformed. In this case, the error may be corrected by performing ageneral RS decoding process.

As another embodiment of the present invention, the error correctionability may be enhanced by using the reliability map created whenconfiguring the RS frame from the soft decision value. Morespecifically, the RS frame decoder 2006 compares the absolute value ofthe soft decision value obtained from the block decoder 2004 to thepre-determined threshold value so as to determine the reliability of thebit values that are decided by the code of the corresponding softdecision value. Then, 8 bits are grouped to configure a byte. Then, thereliability information of the corresponding byte is indicated on thereliability map. Therefore, even if a specific row is determined to haveCRC errors as a result of the CRC syndrome checking process of thecorresponding row, it is not assumed that all of the data bytes includedin the corresponding row have error. Instead, only the data bytes thatare determined to be not reliable, after referring to the reliabilityinformation on the reliability map, are set to have errors. In otherwords, regardless of the presence of CRC errors in the correspondingrow, only the data bytes that are determined to be not reliable (orunreliable) by the reliability map are set as erasure points.

Thereafter, if the number of erasure points for each column is equal toor smaller than the maximum number of errors (e.g., 48), the RS erasuredecoding process is performed on the corresponding the column.Conversely, if the number of erasure points is greater than the maximumnumber of errors (e.g., 48), which may be corrected by the RS erasuredecoding process, a general decoding process is performed on thecorresponding column. In other words, if the number of rows having CRCerrors is greater than the maximum number of errors (e.g., 48), whichmay be corrected by the RS erasure decoding process, either a RS erasuredecoding process or a general RS decoding process is performed on aparticular column in accordance with the number of erasure point withinthe corresponding column, wherein the number is decided based upon thereliability information on the reliability map. When the above-describedprocess is performed, the error correction decoding process is performedin the direction of all of the columns included in the RS frame.Thereafter, the 48 bytes of parity data added to the end of each columnare removed.

FIG. 18 illustrates a block diagram showing the structure of a digitalbroadcast receiving system according to an embodiment of the presentinvention. Referring to FIG. 18, the digital broadcast receiving systemincludes a tuner 3001, a demodulating unit 3002, a demultiplexer 3003,an audio decoder 3004, a video decoder 3005, a native TV applicationmanager 3006, a channel manager 3007, a channel map 3008, a first memory3009, a data decoder 3010, a second memory 3011, a system manager 3012,a data broadcasting application manager 3013, a storage controller 3014,and a third memory 3015. Herein, the third memory 3015 is a mass storagedevice, such as a hard disk drive (HDD) or a memory chip. The tuner 3001tunes a frequency of a specific channel through any one of an antenna,cable, and satellite. Then, the tuner 3001 down-converts the tunedfrequency to an intermediate frequency (IF), which is then outputted tothe demodulating unit 3002. At this point, the tuner 3001 is controlledby the channel manager 3007. Additionally, the result and strength ofthe broadcast signal of the tuned channel are also reported to thechannel manager 3007. The data that are being received by the frequencyof the tuned specific channel include main data, enhanced data, andtable data for decoding the main data and enhanced data.

In the embodiment of the present invention, examples of the enhanceddata may include data provided for data service, such as Javaapplication data, HTML application data, XML data, and so on. The dataprovided for such data services may correspond either to a Java classfile for the Java application, or to a directory file designatingpositions (or locations) of such files. Furthermore, such data may alsocorrespond to an audio file and/or a video file used in eachapplication. The data services may include weather forecast services,traffic information services, stock information services, servicesproviding information quiz programs providing audience participationservices, real time poll, user interactive education programs, gamingservices, services providing information on soap opera (or TV series)synopsis, characters, original sound track, filing sites, servicesproviding information on past sports matches, profiles andaccomplishments of sports players, product information and productordering services, services providing information on broadcast programsby media type, airing time, subject, and so on. The types of dataservices described above are only exemplary and are not limited only tothe examples given herein. Furthermore, depending upon the embodiment ofthe present invention, the enhanced data may correspond to meta data.For example, the meta data use the XML application so as to betransmitted through a DSM-CC protocol.

The demodulating unit 3002 performs demodulation and channelequalization on the signal being outputted from the tuner 3001, therebyidentifying the main data and the enhanced data. Thereafter, theidentified main data and enhanced data are outputted in TS packet units.Examples of the demodulating unit 3002 are shown in FIG. 13 and FIG. 17.The demodulating unit shown in FIG. 13 and FIG. 17 is merely exemplaryand the scope of the present invention is not limited to the examplesset forth herein. In the embodiment given as an example of the presentinvention, only the enhanced data packet outputted from the demodulatingunit 3002 is inputted to the demultiplexer 3003. In this case, the maindata packet is inputted to another demultiplexer (not shown) thatprocesses main data packets. Herein, the storage controller 3014 is alsoconnected to the other demultiplexer in order to store the main dataafter processing the main data packets. The demultiplexer of the presentinvention may also be designed to process both enhanced data packets andmain data packets in a single demultiplexer.

The storage controller 3014 is interfaced with the demultipelxer so asto control instant recording, reserved (or pre-programmed) recording,time shift, and so on of the enhanced data and/or main data. Forexample, when one of instant recording, reserved (or pre-programmed)recording, and time shift is set and programmed in the receiving system(or receiver) shown in FIG. 18, the corresponding enhanced data and/ormain data that are inputted to the demultiplexer are stored in the thirdmemory 3015 in accordance with the control of the storage controller3014. The third memory 3015 may be described as a temporary storage areaand/or a permanent storage area. Herein, the temporary storage area isused for the time shifting function, and the permanent storage area isused for a permanent storage of data according to the user's choice (ordecision).

When the data stored in the third memory 3015 need to be reproduced (orplayed), the storage controller 3014 reads the corresponding data storedin the third memory 3015 and outputs the read data to the correspondingdemultiplexer (e.g., the enhanced data are outputted to thedemultiplexer 3003 shown in FIG. 18). At this point, according to theembodiment of the present invention, since the storage capacity of thethird memory 3015 is limited, the compression encoded enhanced dataand/or main data that are being inputted are directly stored in thethird memory 3015 without any modification for the efficiency of thestorage capacity. In this case, depending upon the reproduction (orreading) command, the data read from the third memory 3015 pass troughthe demultiplexer so as to be inputted to the corresponding decoder,thereby being restored to the initial state.

The storage controller 3014 may control the reproduction (or play),fast-forward, rewind, slow motion, instant replay functions of the datathat are already stored in the third memory 3015 or presently beingbuffered. Herein, the instant replay function corresponds to repeatedlyviewing scenes that the viewer (or user) wishes to view once again. Theinstant replay function may be performed on stored data and also on datathat are currently being received in real time by associating theinstant replay function with the time shift function. If the data beinginputted correspond to the analog format, for example, if thetransmission mode is NTSC, PAL, and so on, the storage controller 3014compression encodes the inputted data and stored the compression-encodeddata to the third memory 3015. In order to do so, the storage controller3014 may include an encoder, wherein the encoder may be embodied as oneof software, middleware, and hardware. Herein, an MPEG encoder may beused as the encoder according to an embodiment of the present invention.The encoder may also be provided outside of the storage controller 3014.

Meanwhile, in order to prevent illegal duplication (or copies) of theinput data being stored in the third memory 3015, the storage controller3014 scrambles the input data and stores the scrambled data in the thirdmemory 3015. Accordingly, the storage controller 3014 may include ascramble algorithm for scrambling the data stored in the third memory3015 and a descramble algorithm for descrambling the data read from thethird memory 3015. Herein, the definition of scramble includesencryption, and the definition of descramble includes decryption. Thescramble method may include using an arbitrary key (e.g., control word)to modify a desired set of data, and also a method of mixing signals.

Meanwhile, the demultiplexer 3003 receives the real-time data outputtedfrom the demodulating unit 3002 or the data read from the third memory3015 and demultiplexes the received data. In the example given in thepresent invention, the demultiplexer 3003 performs demultiplexing on theenhanced data packet. Therefore, in the present invention, the receivingand processing of the enhanced data will be described in detail. Itshould also be noted that a detailed description of the processing ofthe main data will be omitted for simplicity starting from thedescription of the demultiplexer 3003 and the subsequent elements.

The demultiplexer 3003 demultiplexer enhanced data and program specificinformation/program and system information protocol (PSI/PSIP) tablesfrom the enhanced data packet inputted in accordance with the control ofthe data decoder 3010. Thereafter, the demultiplexed enhanced data andPSI/PSIP tables are outputted to the data decoder 3010 in a sectionformat. In order to extract the enhanced data from the channel throughwhich enhanced data are transmitted and to decode the extracted enhanceddata, system information is required. Such system information may alsobe referred to as service information. The system information mayinclude channel information, event information, etc. In the embodimentof the present invention, the PSI/PSIP tables are applied as the systeminformation. However, the present invention is not limited to theexample set forth herein. More specifically, regardless of the name, anyprotocol transmitting system information in a table format may beapplied in the present invention.

The PSI table is an MPEG-2 system standard defined for identifying thechannels and the programs. The PSIP table is an advanced televisionsystems committee (ATSC) standard that can identify the channels and theprograms. The PSI table may include a program association table (PAT), aconditional access table (CAT), a program map table (PMT), and a networkinformation table (NIT). Herein, the PAT corresponds to specialinformation that is transmitted by a data packet having a PID of ‘0’.The PAT transmits PID information of the PMT and PID information of theNIT corresponding to each program. The CAT transmits information on apaid broadcast system used by the transmitting system. The PMT transmitsPID information of a transport stream (TS) packet, in which programidentification numbers and individual bit sequences of video and audiodata configuring the corresponding program are transmitted, and the PIDinformation, in which PCR is transmitted. The NIT transmits informationof the actual transmission network.

The PSIP table may include a virtual channel table (VCT), a system timetable (STT), a rating region table (RRT), an extended text table (ETT),a direct channel change table (DCCT), an event information table (EIT),and a master guide table (MGT). The VCT transmits information on virtualchannels, such as channel information for selecting channels andinformation such as packet identification (PID) numbers for receivingthe audio and/or video data. More specifically, when the VCT is parsed,the PID of the audio/video data of the broadcast program may be known.Herein, the corresponding audio/video data are transmitted within thechannel along with the channel name and the channel number. The STTtransmits information on the current data and timing information. TheRRT transmits information on region and consultation organs for programratings. The ETT transmits additional description of a specific channeland broadcast program. The EIT transmits information on virtual channelevents (e.g., program title, program start time, etc.). The DCCT/DCCSCTtransmits information associated with automatic (or direct) channelchange. And, the MGT transmits the versions and PID information of theabove-mentioned tables included in the PSIP.

Each of the above-described tables included in the PSI/PSIP isconfigured of a basic unit referred to as a “section” and a combinationof one or more sections forms a table. For example, the VCT may bedivided into 256 sections. Herein, one section may include a pluralityof virtual channel information. However, a single set of virtual channelinformation is not divided into two or more sections. At this point, thereceiving system may parse and decode the data for the data service thatare transmitting by using only the tables included in the PSI, or onlythe tables included in the PSIP, or a combination of tables included inboth the PSI and the PSIP. In order to parse and decode the data for thedata service, at least one of the PAT and PMT included in the PSI, andthe VCT included in the PSIP is required. For example, the PAT mayinclude the system information for transmitting the data correspondingto the data service, and the PID of the PMT corresponding to the dataservice data (or program number). The PMT may include the PID of the TSpacket used for transmitting the data service data. The VCT may includeinformation on the virtual channel for transmitting the data servicedata, and the PID of the TS packet for transmitting the data servicedata.

Meanwhile, depending upon the embodiment of the present invention, aDVB-SI may be applied instead of the PSIP. The DVB-SI may include anetwork information table (NIT), a service description table (SDT), anevent information table (EIT), and a time and data table (TDT). TheDVB-SI may be used in combination with the above-described PSI. Herein,the NIT divides the services corresponding to particular networkproviders by specific groups. The NIT includes all tuning informationthat are used during the IRD set-up. The NIT may be used for informingor notifying any change in the tuning information. The SDT includes theservice name and different parameters associated with each servicecorresponding to a particular MPEG multiplex. The EIT is used fortransmitting information associated with all events occurring in theMPEG multiplex. The EIT includes information on the current transmissionand also includes information selectively containing differenttransmission streams that may be received by the IRD. And, the TDT isused for updating the clock included in the IRD.

Furthermore, three selective SI tables (i.e., a bouquet associate table(BAT), a running status table (RST), and a stuffing table (ST)) may alsobe included. More specifically, the bouquet associate table (BAT)provides a service grouping method enabling the IRD to provide servicesto the viewers. Each specific service may belong to at least one‘bouquet’ unit. A running status table (RST) section is used forpromptly and instantly updating at least one event execution status. Theexecution status section is transmitted only once at the changing pointof the event status. Other SI tables are generally transmitted severaltimes. The stuffing table (ST) may be used for replacing or discarding asubsidiary table or the entire SI tables.

In the present invention, the enhanced data included in the payloadwithin the TS packet consist of a digital storage media-command andcontrol (DSM-CC) section format. However, the TS packet including thedata service data may correspond either to a packetized elementarystream (PES) type or to a section type. More specifically, either thePES type data service data configure the TS packet, or the section typedata service data configure the TS packet. The TS packet configured ofthe section type data will be given as the example of the presentinvention. At this point, the data service data are includes in thedigital storage media-command and control (DSM-CC) section. Herein, theDSM-CC section is then configured of a 188-byte unit TS packet.

Furthermore, the packet identification of the TS packet configuring theDSM-CC section is included in a data service table (DST). Whentransmitting the DST, ‘0x95 ’ is assigned as the value of a stream_typefield included in the service location descriptor of the PMT or the VCT.More specifically, when the PMT or VCT stream_type field value is‘0x95’, the receiving system may acknowledge that data broadcastingincluding enhanced data (i.e., the enhanced data) is being received. Atthis point, the enhanced data may be transmitted by a data carouselmethod. The data carousel method corresponds to repeatedly transmittingidentical data on a regular basis.

At this point, according to the control of the data decoder 3010, thedemultiplexer 3003 performs section filtering, thereby discardingrepetitive sections and outputting only the non-repetitive sections tothe data decoder 3010. The demultiplexer 3003 may also output only thesections configuring desired tables (e.g., VCT) to the data decoder 3010by section filtering. Herein, the VCT may include a specific descriptorfor the enhanced data. However, the present invention does not excludethe possibilities of the enhanced data being included in other tables,such as the AMT. The section filtering method may include a method ofverifying the PID of a table defined by the MGT, such as the VCT, priorto performing the section filtering process. Alternatively, the sectionfiltering method may also include a method of directly performing thesection filtering process without verifying the MGT, when the VCTincludes a fixed PID (i.e., a base PID). At this point, thedemultiplexer 3003 performs the section filtering process by referringto a table_id field, a version_number field, a section_number field,etc.

As described above, the method of defining the PID of the VCT broadlyincludes two different methods. Herein, the PID of the VCT is a packetidentifier required for identifying the VCT from other tables. The firstmethod consists of setting the PID of the VCT so that it is dependent tothe MGT. In this case, the receiving system cannot directly verify theVCT among the many PSI and/or PSIP tables. Instead, the receiving systemmust check the PID defined in the MGT in order to read the VCT. Herein,the MGT defines the PID, size, version number, and so on, of diversetables. The second method consists of setting the PID of the VCT so thatthe PID is given a base PID value (or a fixed PID value), thereby beingindependent from the MGT. In this case, unlike in the first method, theVCT according to the present invention may be identified without havingto verify every single PID included in the MGT. Evidently, an agreementon the base PID must be previously made between the transmitting systemand the receiving system.

Meanwhile, in the embodiment of the present invention, the demultiplexer3003 may output only an application information table (AIT) to the datadecoder 3010 by section filtering. The AIT includes information on anapplication being operated in the receiving system for the data service.The AIT may also be referred to as an XAIT, and an AMT. Therefore, anytable including application information may correspond to the followingdescription. When the AIT is transmitted, a value of ‘0x05 ’ may beassigned to a stream_type field of the PMT. The AIT may includeapplication information, such as application name, application version,application priority, application ID, application status (i.e.,auto-start, user-specific settings, kill, etc.), application type (i.e.,Java or HTML), position (or location) of stream including applicationclass and data files, application platform directory, and location ofapplication icon.

In the method for detecting application information for the data serviceby using the AIT, component_tag, original_network_id,transport_stream_id, and service_id fields may be used for detecting theapplication information. The component_tag field designates anelementary stream carrying a DSI of a corresponding object carousel. Theoriginal_network_id field indicates a DVB-SI original_network_id of theTS providing transport connection. The transport_stream_id fieldindicates the MPEG TS of the TS providing transport connection, and theservice_id field indicates the DVB-SI of the service providing transportconnection. Information on a specific channel may be obtained by usingthe original_network_id field, the transport_stream_id field, and theservice_id field. The data service data, such as the application data,detected by using the above-described method may be stored in the secondmemory 3011 by the data decoder 3010.

The data decoder 3010 parses the DSM-CC section configuring thedemultiplexed enhanced data. Then, the enhanced data corresponding tothe parsed result are stored as a database in the second memory 3011.The data decoder 3010 groups a plurality of sections having the sametable identification (table_id) so as to configure a table, which isthen parsed. Thereafter, the parsed result is stored as a database inthe second memory 3011. At this point, by parsing data and/or sections,the data decoder 3010 reads all of the remaining actual section datathat are not section-filtered by the demultiplexer 3003. Then, the datadecoder 3010 stores the read data to the second memory 3011. The secondmemory 3011 corresponds to a table and data carousel database storingsystem information parsed from tables and enhanced data parsed from theDSM-CC section. Herein, a table_id field, a section_number field, and alast_section_number field included in the table may be used to indicatewhether the corresponding table is configured of a single section or aplurality of sections. For example, TS packets having the PID of the VCTare grouped to form a section, and sections having table identifiersallocated to the VCT are grouped to form the VCT.

When the VCT is parsed, information on the virtual channel to whichenhanced data are transmitted may be obtained. The obtained applicationidentification information, service component identificationinformation, and service information corresponding to the data servicemay either be stored in the second memory 3011 or be outputted to thedata broadcasting application manager 3013. In addition, reference maybe made to the application identification information, service componentidentification information, and service information in order to decodethe data service data. Alternatively, such information may also preparethe operation of the application program for the data service.Furthermore, the data decoder 3010 controls the demultiplexing of thesystem information table, which corresponds to the information tableassociated with the channel and events. Thereafter, an A.V PID list maybe transmitted to the channel manager 3007.

The channel manager 3007 may refer to the channel map 3008 in order totransmit a request for receiving system-related information data to thedata decoder 3010, thereby receiving the corresponding result. Inaddition, the channel manager 3007 may also control the channel tuningof the tuner 3001. Furthermore, the channel manager 3007 may directlycontrol the demultiplexer 3003, so as to set up the A/V PID, therebycontrolling the audio decoder 3004 and the video decoder 3005. The audiodecoder 3004 and the video decoder 3005 may respectively decode andoutput the audio data and video data demultiplexed from the main datapacket. Alternatively, the audio decoder 3004 and the video decoder 3005may respectively decode and output the audio data and video datademultiplexed from the enhanced data packet. Meanwhile, when theenhanced data include data service data, and also audio data and videodata, it is apparent that the audio data and video data demultiplexed bythe demultiplexer 3003 are respectively decoded by the audio decoder3004 and the video decoder 3005. For example, an audio-coding (AC)-3decoding algorithm may be applied to the audio decoder 3004, and aMPEG-2 decoding algorithm may be applied to the video decoder 3005.

Meanwhile, the native TV application manager 3006 operates a nativeapplication program stored in the first memory 3009, thereby performinggeneral functions such as channel change. The native application programrefers to software stored in the receiving system upon shipping of theproduct. More specifically, when a user request (or command) istransmitted to the receiving system through a user interface (UI), thenative TV application manger 3006 displays the user request on a screenthrough a graphic user interface (GUI), thereby responding to the user'srequest. The user interface receives the user request through an inputdevice, such as a remote controller, a key pad, a jog controller, an atouch-screen provided on the screen, and then outputs the received userrequest to the native TV application manager 3006 and the databroadcasting application manager 3013. Furthermore, the native TVapplication manager 3006 controls the channel manager 3007, therebycontrolling channel-associated, such as the management of the channelmap 3008, and controlling the data decoder 3010. The native TVapplication manager 3006 also controls the GUI of the overall receivingsystem, thereby storing the user request and status of the receivingsystem in the first memory 3009 and restoring the stored information.

The channel manager 3007 controls the tuner 3001 and the data decoder3010, so as to managing the channel map 3008 so that it can respond tothe channel request made by the user. More specifically, channel manager3007 sends a request to the data decoder 3010 so that the tablesassociated with the channels that are to be tuned are parsed. Theresults of the parsed tables are reported to the channel manager 3007 bythe data decoder 3010. Thereafter, based on the parsed results, thechannel manager 3007 updates the channel map 3008 and sets up a PID inthe demultiplexer 3003 for demultiplexing the tables associated with thedata service data from the enhanced data.

The system manager 3012 controls the booting of the receiving system byturning the power on or off. Then, the system manager 3012 stores ROMimages (including downloaded software images) in the first memory 3009.More specifically, the first memory 3009 stores management programs suchas operating system (OS) programs required for managing the receivingsystem and also application program executing data service functions.The application program is a program processing the data service datastored in the second memory 3011 so as to provide the user with the dataservice. If the data service data are stored in the second memory 3011,the corresponding data service data are processed by the above-describedapplication program or by other application programs, thereby beingprovided to the user. The management program and application programstored in the first memory 3009 may be updated or corrected to a newlydownloaded program. Furthermore, the storage of the stored managementprogram and application program is maintained without being deleted evenif the power of the system is shut down. Therefore, when the power issupplied the programs may be executed without having to be newlydownloaded once again.

The application program for providing data service according to thepresent invention may either be initially stored in the first memory3009 upon the shipping of the receiving system, or be stored in thefirst 3009 after being downloaded. The application program for the dataservice (i.e., the data service providing application program) stored inthe first memory 3009 may also be deleted, updated, and corrected.Furthermore, the data service providing application program may bedownloaded and executed along with the data service data each time thedata service data are being received.

When a data service request is transmitted through the user interface,the data broadcasting application manager 3013 operates thecorresponding application program stored in the first memory 3009 so asto process the requested data, thereby providing the user with therequested data service. And, in order to provide such data service, thedata broadcasting application manager 3013 supports the graphic userinterface (GUT). Herein, the data service may be provided in the form oftext (or short message service (SMS)), voice message, still image, andmoving image. The data broadcasting application manager 3013 may beprovided with a platform for executing the application program stored inthe first memory 3009. The platform may be, for example, a Java virtualmachine for executing the Java program. Hereinafter, an example of thedata broadcasting application manager 3013 executing the data serviceproviding application program stored in the first memory 3009, so as toprocess the data service data stored in the second memory 3011, therebyproviding the user with the corresponding data service will now bedescribed in detail.

Assuming that the data service corresponds to a traffic informationservice, the data service according to the present invention is providedto the user of a receiving system that is not equipped with anelectronic map and/or a GPS system in the form of at least one of a text(or short message service (SMS)), a voice message, a graphic message, astill image, and a moving image. In this case, is a GPS module ismounted on the receiving system shown in FIG. 18, the GPS modulereceives satellite signals transmitted from a plurality of low earthorbit satellites and extracts the current position (or location)information (e.g., longitude, latitude, altitude), thereby outputtingthe extracted information to the data broadcasting application manager3013.

At this point, it is assumed that the electronic map includinginformation on each link and nod and other diverse graphic informationare stored in one of the second memory 3011, the first memory 3009, andanother memory that is not shown. More specifically, according to therequest made by the data broadcasting application manager 3013, the dataservice data stored in the second memory 3011 are read and inputted tothe data broadcasting application manager 3013. The data broadcastingapplication manager 3013 translates (or deciphers) the data service dataread from the second memory 3011, thereby extracting the necessaryinformation according to the contents of the message and/or a controlsignal.

FIG. 19 illustrates a block diagram showing the structure of a digitalbroadcast (or television) receiving system according to anotherembodiment of the present invention. Referring to FIG. 19, the digitalbroadcast receiving system includes a tuner 4001, a demodulating unit4002, a demultiplexer 4003, a first descrambler 4004, an audio decoder4005, a video decoder 4006, a second descrambler 4007, an authenticationunit 4008, a native TV application manager 4009, a channel manager 4010,a channel map 4011, a first memory 4012, a data decoder 4013, a secondmemory 4014, a system manager 4015, a data broadcasting applicationmanager 4016, a storage controller 4017, a third memory 4018, and atelecommunication module 4019. Herein, the third memory 4018 is a massstorage device, such as a hard disk drive (HDD) or a memory chip. Also,during the description of the digital broadcast (or television or DTV)receiving system shown in FIG. 19, the components that are identical tothose of the digital broadcast receiving system of FIG. 18 will beomitted for simplicity.

As described above, in order to provide services for preventing illegalduplication (or copies) or illegal viewing of the enhanced data and/ormain data that are transmitted by using a broadcast network, and toprovide paid broadcast services, the transmitting system may generallyscramble and transmit the broadcast contents. Therefore, the receivingsystem needs to descrample the scrambled broadcast contents in order toprovide the user with the proper broadcast contents. Furthermore, thereceiving system may generally be processed with an authenticationprocess with an anuthnetication means before the descrambling process.Hereinafter, the receiving system including an authentication means anda descrambling means according to an embodiment of the present inventionwill now be described in detail.

According to the present invention, the receiving system may be providedwith a descrambling means receiving scrambled broadcasting contents andan authentication means authenticating (or verifying) whether thereceiving system is entitled to receive the descrambled contents.Hereinafter, the descrambling means will be referred to as first andsecond descramblers 4004 and 4007, and the authentication means will bereferred to as an authentication unit 4008. Such naming of thecorresponding components is merely exemplary and is not limited to theterms suggested in the description of the present invention. Forexample, the units may also be referred to as a decryptor. Although FIG.19 illustrates an example of the descramblers 4004 and 4007 and theauthentication unit 4008 being provided inside the receiving system,each of the descramblers 4004 and 4007 and the authentication unit 4008may also be separately provided in an internal or external module.Herein, the module may include a slot type, such as a SD or CF memory, amemory stick type, a USB type, and so on, and may be detachably fixed tothe receiving system.

As described above, when the authentication process is performedsuccessfully by the authentication unit 4008, the scrambled broadcastingcontents are descrambled by the descramblers 4004 and 4007, therebybeing provided to the user. At this point, a variety of theauthentication method and descrambling method may be used herein.However, an agreement on each corresponding method should be madebetween the receiving system and the transmitting system. Hereinafter,the authentication and descrambling methods will now be described, andthe description of identical components or process steps will be omittedfor simplicity.

The receiving system including the authentication unit 4008 and thedescramblers 4004 and 4007 will now be described in detail. Thereceiving system receives the scrambled broadcasting contents throughthe tuner 4001 and the demodulating unit 4002. Then, the system manager4015 decides whether the received broadcasting contents have beenscrambled. Herein, the demodulating unit 4002 may be included as ademodulating means according to embodiments of the present invention asdescribed in FIG. 13 and FIG. 17. However, the present invention is notlimited to the examples given in the description set forth herein. Ifthe system manager 4015 decides that the received broadcasting contentshave been scrambled, then the system manager 4015 controls the system tooperate the authentication unit 4008. As described above, theauthentication unit 4008 performs an authentication process in order todecide whether the receiving system according to the present inventioncorresponds to a legitimate host entitled to receive the paidbroadcasting service. Herein, the authentication process may vary inaccordance with the authentication methods.

For example, the authentication unit 4008 may perform the authenticationprocess by comparing an IP address of an IP datagram within the receivedbroadcasting contents with a specific address of a corresponding host.At this point, the specific address of the corresponding receivingsystem (or host) may be a MAC address. More specifically, theauthentication unit 4008 may extract the IP address from thedecapsulated IP datagram, thereby obtaining the receiving systeminformation that is mapped with the IP address. At this point, thereceiving system should be provided, in advance, with information (e.g.,a table format) that can map the IP address and the receiving systeminformation. Accordingly, the authentication unit 4008 performs theauthentication process by determining the conformity between the addressof the corresponding receiving system and the system information of thereceiving system that is mapped with the IP address. In other words, ifthe authentication unit 4008 determines that the two types ofinformation conform to one another, then the authentication unit 4008determines that the receiving system is entitled to receive thecorresponding broadcasting contents.

In another example, standardized identification information is definedin advance by the receiving system and the transmitting system. Then,the identification information of the receiving system requesting thepaid broadcasting service is transmitted by the transmitting system.Thereafter, the receiving system determines whether the receivedidentification information conforms with its own unique identificationnumber, so as to perform the authentication process. More specifically,the transmitting system creates a database for storing theidentification information (or number) of the receiving systemrequesting the paid broadcasting service. Then, if the correspondingbroadcasting contents are scrambled, the transmitting system includesthe identification information in the EMM, which is then transmitted tothe receiving system.

If the corresponding broadcasting contents are scrambled, messages(e.g., entitlement control message (ECM), entitlement management message(EMM)), such as the CAS information, mode information, message positioninformation, that are applied to the scrambling of the broadcastingcontents are transmitted through a corresponding data header or anotherdata packet. The ECM may include a control word (CW) used for scramblingthe broadcasting contents. At this point, the control word may beencoded with an authentication key. The EMM may include anauthentication key and entitlement information of the correspondingdata. Herein, the authentication key may be encoded with a receivingsystem-specific distribution key. In other words, assuming that theenhanced data are scrambled by using the control word, and that theauthentication information and the descrambling information aretransmitted from the transmitting system, the transmitting systemencodes the CW with the authentication key and, then, includes theencoded CW in the entitlement control message (ECM), which is thentransmitted to the receiving system. Furthermore, the transmittingsystem includes the authentication key used for encoding the CW and theentitlement to receive data (or services) of the receiving system (i.e.,a standardized serial number of the receiving system that is entitled toreceive the corresponding broadcasting service or data) in theentitlement management message (EMM), which is then transmitted to thereceiving system.

Accordingly, the authentication unit 4008 of the receiving systemextracts the identification information of the receiving system and theidentification information included in the EMM of the broadcastingservice that is being received. Then, the authentication unit 4008determines whether the identification information conform to each other,so as to perform the authentication process. More specifically, if theauthentication unit 4008 determines that the information conform to eachother, then the authentication unit 4008 eventually determines that thereceiving system is entitled to receive the request broadcastingservice.

In yet another example, the authentication unit 4008 of the receivingsystem may be detachably fixed to an external module. In this case, thereceiving system is interfaced with the external module through a commoninterface (CI). In other words, the external module may receive the datascrambled by the receiving system through the common interface, therebyperforming the descrambling process of the received data. Alternatively,the external module may also transmit only the information required forthe descrambling process to the receiving system. The common interfaceis configured on a physical layer and at least one protocol layer.Herein, in consideration of any possible expansion of the protocol layerin a later process, the corresponding protocol layer may be configuredto have at least one layer that can each provide an independentfunction.

The external module may either consist of a memory or card havinginformation on the key used for the scrambling process and otherauthentication information but not including any descrambling function,or consist of a card having the above-mentioned key information andauthentication information and including the descrambling function. Boththe receiving system and the external module should be authenticated inorder to provide the user with the paid broadcasting service provided(or transmitted) from the transmitting system. Therefore, thetransmitting system can only provide the corresponding paid broadcastingservice to the authenticated pair of receiving system and externalmodule.

Additionally, an authentication process should also be performed betweenthe receiving system and the external module through the commoninterface. More specifically, the module may communicate with the systemmanager 4015 included in the receiving system through the commoninterface, thereby authenticating the receiving system. Alternatively,the receiving system may authenticate the module through the commoninterface. Furthermore, during the authentication process, the modulemay extract the unique ID of the receiving system and its own unique IDand transmit the extracted IDs to the transmitting system. Thus, thetransmitting system may use the transmitted ID values as informationdetermining whether to start the requested service or as paymentinformation. Whenever necessary, the system manager 4015 transmits thepayment information to the remote transmitting system through thetelecommunication module 4019.

The authentication unit 4008 authenticates the corresponding receivingsystem and/or the external module. Then, if the authentication processis successfully completed, the authentication unit 4008 certifies thecorresponding receiving system and/or the external module as alegitimate system and/or module entitled to receive the requested paidbroadcasting service. In addition, the authentication unit 4008 may alsoreceive authentication-associated information from a mobiletelecommunications service provider to which the user of the receivingsystem is subscribed, instead of the transmitting system providing therequested broadcasting service. In this case, theauthentication-association information may either be scrambled by thetransmitting system providing the broadcasting service and, then,transmitted to the user through the mobile telecommunications serviceprovider, or be directly scrambled and transmitted by the mobiletelecommunications service provider. Once the authentication process issuccessfully completed by the authentication unit 4008, the receivingsystem may descramble the scrambled broadcasting contents received fromthe transmitting system. At this point, the descrambling process isperformed by the first and second descramblers 4004 and 4007. Herein,the first and second descramblers 4004 and 4007 may be included in aninternal module or an external module of the receiving system.

The receiving system is also provided with a common interface forcommunicating with the external module including the first and seconddescramblers 4004 and 4007, so as to perform the descrambling process.More specifically, the first and second descramblers 4004 and 4007 maybe included in the module or in the receiving system in the form ofhardware, middleware or software. Herein, the descramblers 4004 and 4007may be included in any one of or both of the module and the receivingsystem. If the first and second descramblers 4004 and 4007 are providedinside the receiving system, it is advantageous to have the transmittingsystem (i.e., at least any one of a service provider and a broadcaststation) scramble the corresponding data using the same scramblingmethod.

Alternatively, if the first and second descramblers 4004 and 4007 areprovided in the external module, it is advantageous to have eachtransmitting system scramble the corresponding data using differentscrambling methods. In this case, the receiving system is not requiredto be provided with the descrambling algorithm corresponding to eachtransmitting system. Therefore, the structure and size of receivingsystem may be simplified and more compact. Accordingly, in this case,the external module itself may be able to provide CA functions, whichare uniquely and only provided by each transmitting systems, andfunctions related to each service that is to be provided to the user.The common interface enables the various external modules and the systemmanager 4015, which is included in the receiving system, to communicatewith one another by a single communication method. Furthermore, sincethe receiving system may be operated by being connected with at leastone or more modules providing different services, the receiving systemmay be connected to a plurality of modules and controllers.

In order to maintain successful communication between the receivingsystem and the external module, the common interface protocol includes afunction of periodically checking the status of the oppositecorrespondent. By using this function, the receiving system and theexternal module is capable of managing the status of each oppositecorrespondent. This function also reports the user or the transmittingsystem of any malfunction that may occur in any one of the receivingsystem and the external module and attempts the recovery of themalfunction.

In yet another example, the authentication process may be performedthrough software. More specifically, when a memory card having CASsoftware downloaded, for example, and stored therein in advanced isinserted in the receiving system, the receiving system receives andloads the CAS software from the memory card so as to perform theauthentication process. In this example, the CAS software is read outfrom the memory card and stored in the first memory 4012 of thereceiving system. Thereafter, the CAS software is operated in thereceiving system as an application program. According to an embodimentof the present invention, the CAS software is mounted on (or stored) ina middleware platform and, then executed. A Java middleware will begiven as an example of the middleware included in the present invention.Herein, the CAS software should at least include information requiredfor the authentication process and also information required for thedescrambling process.

Therefore, the authentication unit 4008 performs authenticationprocesses between the transmitting system and the receiving system andalso between the receiving system and the memory card. At this point, asdescribed above, the memory card should be entitled to receive thecorresponding data and should include information on a normal receivingsystem that can be authenticated. For example, information on thereceiving system may include a unique number, such as a standardizedserial number of the corresponding receiving system. Accordingly, theauthentication unit 4008 compares the standardized serial numberincluded in the memory card with the unique information of the receivingsystem, thereby performing the authentication process between thereceiving system and the memory card.

If the CAS software is first executed in the Java middleware base, thenthe authentication between the receiving system and the memory card isperformed. For example, when the unique number of the receiving systemstored in the memory card conforms to the unique number of the receivingsystem read from the system manager 4015, then the memory card isverified and determined to be a normal memory card that may be used inthe receiving system. At this point, the CAS software may either beinstalled in the first memory 4012 upon the shipping of the presentinvention, or be downloaded to the first memory 4012 from thetransmitting system or the module or memory card, as described above.Herein, the descrambling function may be operated by the databroadcasting application manger 4016 as an application program.

Thereafter, the CAS software parses the EMM/ECM packets outputted fromthe demultiplexer 4003, so as to verify whether the receiving system isentitled to receive the corresponding data, thereby obtaining theinformation required for descrambling (i.e., the CW) and providing theobtained CW to the descramblers 4004 and 4007. More specifically, theCAS software operating in the Java middleware platform first reads outthe unique (or serial) number of the receiving system from thecorresponding receiving system and compares it with the unique number ofthe receiving system transmitted through the EMM, thereby verifyingwhether the receiving system is entitled to receive the correspondingdata. Once the receiving entitlement of the receiving system isverified, the corresponding broadcasting service information transmittedto the ECM and the entitlement of receiving the correspondingbroadcasting service are used to verify whether the receiving system isentitled to receive the corresponding broadcasting service. Once thereceiving system is verified to be entitled to receive the correspondingbroadcasting service, the authentication key transmitted to the EMM isused to decode (or decipher) the encoded CW, which is transmitted to theECM, thereby transmitting the decoded CW to the descramblers 4004 and4007. Each of the descramblers 4004 and 4007 uses the CW to descramblethe broadcasting service.

Meanwhile, the CAS software stored in the memory card may be expanded inaccordance with the paid service which the broadcast station is toprovide. Additionally, the CAS software may also include otheradditional information other than the information associated with theauthentication and descrambling. Furthermore, the receiving system maydownload the CAS software from the transmitting system so as to upgrade(or update) the CAS software originally stored in the memory card. Asdescribed above, regardless of the type of broadcast receiving system,as long as an external memory interface is provided, the presentinvention may embody a CAS system that can meet the requirements of alltypes of memory card that may be detachably fixed to the receivingsystem. Thus, the present invention may realize maximum performance ofthe receiving system with minimum fabrication cost, wherein thereceiving system may receive paid broadcasting contents such asbroadcast programs, thereby acknowledging and regarding the variety ofthe receiving system. Moreover, since only the minimum applicationprogram interface is required to be embodied in the embodiment of thepresent invention, the fabrication cost may be minimized, therebyeliminating the manufacturer's dependence on CAS manufacturers.Accordingly, fabrication costs of CAS equipments and management systemsmay also be minimized.

Meanwhile, the descramblers 4004 and 4007 may be included in the moduleeither in the form of hardware or in the form of software. In this case,the scrambled data that being received are descrambled by the module andthen demodulated. Also, if the scrambled data that are being receivedare stored in the third memory 4018, the received data may bedescrambled and then stored, or stored in the memory at the point ofbeing received and then descrambled later on prior to being played (orreproduced). Thereafter, in case scramble/descramble algorithms areprovided in the storage controller 4017, the storage controller 4017scrambles the data that are being received once again and then storesthe re-scrambled data to the third memory 4018.

In yet another example, the descrambled broadcasting contents(transmission of which being restricted) are transmitted through thebroadcasting network. Also, information associatedwith theauthentication and descrambling of data in order to disable thereceiving restrictions of the corresponding data are transmitted and/orreceived through the telecommunications module 4019. Thus, the receivingsystem is able to perform reciprocal (or two-way) communication. Thereceiving system may either transmit data to the telecommunicationmodule within the transmitting system or be provided with the data fromthe telecommunication module within the transmitting system. Herein, thedata correspond to broadcasting data that are desired to be transmittedto or from the transmitting system, and also unique information (i.e.,identification information) such as a serial number of the receivingsystem or MAC address.

The telecommunication module 4019 included in the receiving systemprovides a protocol required for performing reciprocal (or two-way)communication between the receiving system, which does not support thereciprocal communication function, and the telecommunication moduleincluded in the transmitting system. Furthermore, the receiving systemconfigures a protocol data unit (PDU) using a tag-length-value (TLV)coding method including the data that are to be transmitted and theunique information (or ID information). Herein, the tag field includesindexing of the corresponding PDU. The length field includes the lengthof the value field. And, the value field includes the actual data thatare to be transmitted and the unique number (e.g., identificationnumber) of the receiving system.

The receiving system may configure a platform that is equipped with theJava platform and that is operated after downloading the Javaapplication of the transmitting system to the receiving system throughthe network. In this case, a structure of downloading the PDU includingthe tag field arbitrarily defined by the transmitting system from astorage means included in the receiving system and then transmitting thedownloaded PDU to the telecommunication module 4019 may also beconfigured. Also, the PDU may be configured in the Java application ofthe receiving system and then outputted to the telecommunication module4019. The PDU may also be configured by transmitting the tag value, theactual data that are to be transmitted, the unique information of thecorresponding receiving system from the Java application and byperforming the TLV coding process in the receiving system. Thisstructure is advantageous in that the firmware of the receiving systemis not required to be changed even if the data (or application) desiredby the transmitting system is added.

The telecommunication module within the transmitting system eithertransmits the PDU received from the receiving system through a wirelessdata network or configures the data received through the network into aPDU which is transmitted to the host. At this point, when configuringthe PDU that is to be transmitted to the host, the telecommunicationmodule within the transmitting end may include unique information (e.g.,IP address) of the transmitting system which is located in a remotelocation. Additionally, in receiving and transmitting data through thewireless data network, the receiving system may be provided with acommon interface, and also provided with a WAP, CDMA 1x EV-DO, which canbe connected through a mobile telecommunication base station, such asCDMA and GSM, and also provided with a wireless LAN, mobile Internet,WiEro, WiMax, which can be connected through an access point. Theabove-described receiving system corresponds to the system that is notequipped with a telecommunication function. However, a receiving systemequipped with telecommunication function does not require thetelecommunication module 4019.

The broadcasting data being transmitted and received through theabove-described wireless data network may include data required forperforming the function of limiting data reception. Meanwhile, thedemultiplexer 4003 receives either the real-time data outputted from thedemodulating unit 4002 or the data read from the third memory 4018,thereby performing demultiplexing. In this embodiment of the presentinvention, the demultiplexer 4003 performs demultiplexing on theenhanced data packet. Similar process steps have already been describedearlier in the description of the present invention. Therefore, adetailed of the process of demultiplexing the enhanced data will beomitted for simplicity.

The first descrambler 4004 receives the demultiplexed signals from thedemultiplexer 4003 and then descrambles the received signals. At thispoint, the first descrambler 4004 may receive the authentication resultreceived from the authentication unit 4008 and other data required forthe descrambling process, so as to perform the descrambling process. Theaudio decoder 4005 and the video decoder 400G receive the signalsdescrambled by the first descrambler 4004, which are then decoded andoutputted. Alternatively, if the first descrambler 4004 did not performthe descrambling process, then the audio decoder 4005 and the videodecoder 4006 directly decode and output the received signals. In thiscase, the decoded signals are received and then descrambled by thesecond descrambler 4007 and processed accordingly.

As described above, the digital television (DTV) transmitting system andreceiving system and method processing broadcast signal according to thepresent invention have advantages in that errors rarely occur whenenhanced data is transmitted through channels and they also arecompatible with the conventional receivers. Also, the present inventioncan receive enhanced data without errors through channels in which ghostimages and noise are a serious problem, compared with the conventionalsystem.

Also, in order to group a plurality of enhanced data packets havinginformation, multiplex the group with main data, and transmit them, thepresent invention stratifies the group to form a plurality of regions,and classifies types of inserted data, and processing methods, etc.,according to characteristics of stratified regions. Therefore, receivingperformance of a receiving system can be enhanced. Especially, aspre-processes are performed differently according to types of datainserted to the stratified regions in the group and types of inputtedenhanced data, receiving performance of a receiving system can befurther enhanced.

Also, as recurrence turbo decoding for the enhanced data is performed inthe receiving end, decoding performance of the receiving system can beincreased.

In addition, the present invention is more effective when it is appliedto portable and mobile receivers whose channels vary significantly.Also, the present invention clearly shows its effect in receivers whichrequire resistance to noise.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1-30. (canceled)
 31. A digital television (DTV) receiver for processingdigital broadcast data, the DTV receiver comprising: a tuner forreceiving a broadcast signal, wherein the broadcast signal is processedin a DTV transmitter by: randomizing enhanced data, generating aReed-Solomon (RS) frame by adding RS parity data and cyclic redundancycheck (CRC) data to the randomized enhanced data, encoding the enhanceddata in the RS frame with an encoding rate of 1/H, wherein H≧2,interleaving symbols corresponding to the encoded enhanced data in asymbol interleaver, wherein the symbol interleaver interleaves thesymbols by: calculating L, wherein L=2^(m) and m is an integer, listingall permuted positions P′(i) in ascending order of i according to thefollowing equation: P′(i)={89*i*(i+1)/2} mod L, wherein i is a naturalnumber from 0 to L−1, discarding all P′(i) that are P′(i)≧B, wherein Bis a block length of symbols input to the symbol interleaver, andcondensing the list by, starting with a lowest i, shifting P(i) entriesto the left to fill empty locations created by the discarding step,mapping enhanced data corresponding to the interleaved symbols into datagroups, wherein each data group further includes known data sequences,signaling information and moving picture experts group (MPEG) headerplace holders, deinterleaving the data groups, replacing the MPEG headerplace holders in the deinterleaved data groups with MPEG header data andoutputting enhanced data packets, and interleaving the enhanced datapackets; a demodulator for demodulating the received broadcast signal;an equalizer for compensating channel distortion of the demodulatedbroadcast signal using at least one of the known data sequences; a firstdecoder for turbo-decoding the enhanced data in the equalized broadcastsignal; and a second decoder for CRC-decoding and RS-decoding theturbo-decoded enhanced data.
 32. The DTV receiver of claim 31, whereinthe equalizer compensates channel distortion of the demodulatedbroadcast signal by estimating channel impulse responses (CIRs) usingthe at least one of the known data sequences.
 33. The DTV receiver ofclaim 32, wherein the equalizer compensates channel distortion of thedemodulated broadcast signal by interpolating the CIRs.
 34. The DTVreceiver of claim 32, wherein the equalizer compensates channeldistortion of the demodulated broadcast signal by extrapolating theCIRs.
 35. The DTV receiver of claim 31, wherein at least two of theknown data sequences have different lengths and wherein the signalinginformation includes information associated with the data group.
 36. Amethod of processing digital broadcast data in a digital television(DTV) receiver, the method comprising: receiving, by a tuner, abroadcast signal, wherein the broadcast signal is processed in a DTVtransmitter by: randomizing enhanced data, generating a Reed-Solomon(RS) frame by adding RS parity data and cyclic redundancy check (CRC)data to the randomized enhanced data, encoding the enhanced data in theRS frame with an encoding rate of 1/H, wherein H≧2, interleaving symbolscorresponding to the encoded enhanced data in a symbol interleaver,wherein the symbol interleaver interleaves the symbols by: calculatingL, where L=2^(m), where m is an integer, listing all permuted positionsP′(i) in ascending order of i according to the following equation:P′(i)={89*i*(i+1)/2} mod L, wherein i is a natural number from 0to L−1,discarding all P′(i) that are P′(i)≧B, wherein B is a block length ofsymbols input to the symbol interleaver, and condensing the list by,starting with a lowest i, shifting P(i) entries to the left to fillempty locations created by the discarding step, mapping enhanced datacorresponding to the interleaved symbols into data groups, wherein eachdata group further includes known data sequences, signaling informationand moving picture experts group (MPEG) header place holders,deinterleaving the data groups, replacing the MPEG header place holdersin the deinterleaved data groups with MPEG header data and outputtingenhanced data packets, and interleaving the enhanced data packets,demodulating, by a demodulator, the received broadcast signal;compensating, by an equalizer, channel distortion of the demodulatedbroadcast signal using at least one of the known data sequences;turbo-decoding, by a first decoder, the enhanced data in the equalizedbroadcast signal; and CRC-decoding and RS-decoding, by a second decoder,the turbo-decoded enhanced data.
 37. The method of claim 36, whereincompensating channel distortion of the demodulated broadcast signalcompensates channel distortion of the demodulated broadcast signal byestimating channel impulse responses (CIRs) using the at least one ofthe known data sequences.
 38. The method of claim 37, whereincompensating channel distortion of the demodulated broadcast signalcompensates channel distortion of the demodulated broadcast signal byinterpolating the CIRs.
 39. The method of claim 37, wherein compensatingchannel distortion of the demodulated broadcast signal compensateschannel distortion of the demodulated broadcast signal by extrapolatingthe CIRs.
 40. The method of claim 36, wherein at least two of the knowndata sequences have different lengths and wherein the signalinginformation includes information associated with the data group.